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COPYRIGHT DEPOSIT. 



DEVELOPMENTAL PATHOLOGY 



A Study in Degenerative 
Evolution 



By 

EUGENE S. TALBOT, M.S., D.D.S., M.D., LL.D. 



Professor of Stomatology, Bennett Medical College, (Loyola University) ; 
Corresponding member, Budapest Royal Society of Physicians, 
honorary president International Association of 
Stomatology, 1907, Paris. 



WITH 346 ILLUSTRATIONS 




RICHARD G. BADGER 

THE GORHAM PRESS 
BOSTON 



Copyright 1911 by Richard G. Badger 
All Rights Reserved 



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The Gorham Press, Boston, Mass., U. S. A. 



$b*W> 



©CLA303310 



It has been the author s privilege to be the pupil 

of 
PROF. JAMES GEORGE KIERNAN 

to whom 
this book is respectfully dedicated 



PREFACE 

THE object of this book, tersely stated, is to show: 
First, that the ontogeny of man, his structures and organs, is a 
modified recapitulation of his phylogeny in development. 

Second, that as the vertebral phase appears early in embryogeny, an 
unstable nervous system checked by parental defects, eruptive fevers, and 
other agencies at the periods of stress in the child, affects phylogeny and 
ontogeny. 

The paramount practical purpose of the book, therefore, is to correct 
current erroneous conceptions of heredity, by showing that neither exces- 
sive nor arrested development is inherited directly from the parent. Chil- 
dren born with structures and organs which exhibit a departure from the 
type, are said to inherit these defects. Upon investigation, however, none 
of the defects are to be found in the family for generations; in the seeming 
default of heredity to account for the departures from the type, the ordinary 
mind fails to understand them. The real key to the situation lies in the 
truth that human heredity cannot be considered to any purpose, without 
taking into account intrauterine education, environment and development. 
With the object of presenting these conditions in their proper relationship 
this work is offered. It is by no means complete. Many pathologic 
conditions of structures and organs are necessarily not enumerated. It 
is hoped that other workers in this field will continue investigations and 
carry views, herein outlined, to a more extended issue. It is not intended 
to take the place of any other researches detailed in preceding works, since 
this work is intended merely to lay down general principles. 

Much of the material on phylogeny of the teeth is taken from Richard 
Owen, (Odontography) and Tomes, (Dental Anatomy ), standard works. 

The author has utilized facts, collected by other writers. Occasionally 
the exact language is cited. The works consulted with names of their 
authors appear in the back of this work. These works are especially 
adapted to form a part of the working library of every practitioner. 

There are many repetitions, beneficial, since they familiarize the 
student with general laws applicable to each pathologic condition. 

The author is under obligations to Dr. Charles H. Ward, of Rochester, 
New York, for preparation and arrangement of the fetal and infant skulls, 
especially prepared for this work; to Dr. Vida A. Latham for assistance 
in microphotography of the dental pulp; to Dr. James G. Kiernan for 
suggestions; to Dr. Thomas G. Atkinson for assistance in preparing the 
manuscript for the press; to Capt. M. P. Evans of the Identification De- 



vi PREFACE 

partment of Police of the City of Chicago, and to the Superintendent of 
the Illinois State Reformatory, at Pontiac, for photographs of criminals; 
to Miss Helen Dunning for illustrations and to Blomgren Bros. & Company, 
of Chicago, for electroplates. 

Eugene S. Talbot 



TABLE OF CONTENTS 

PAGE 

Preface v 

Introduction • xix 

CHAPTER I 

Nature of Living Beings 1 

CHAPTER II 

Development of Man 15 

CHAPTER III 

Development of Organs: The Brain 28 

CHAPTER IV 

Developent of Organs: The Heart and Great Arteries 38 

CHAPTER V 

Development of Organs: The Liver 47 

CHAPTER VI 

Development of Organs : The Kidney 52 

CHAPTER VII 

Development of Organs: The Head and Face 59 

CHAPTER VIII 

Periods of Stress • 83 

CHAPTER IX 

An Unstable Nervous System the Cause of Nutritive Disturbances: 

Checks on Excessive Action not Properly Developed 97 

CHAPTER X 

An Unstable Nervous System the Cause of Nutritive Disturbances: 

Checks on Excessive Action Weakened 109 

CHAPTER XI 

Nervous Effects of Relaxed Check Action 124 

CHAPTER XII 

Constitutional Degeneracies due to Check Action: Of Normal Struc- 
tures in Man's Present Evolution 129 

CHAPTER XIII 

Constitutional Degeneracies due to Decreased Check Action: Of 

Structures that have passed in Man's Present Evolution 155 

CHAPTER XIV 

Constitutional Degeneracies due to Check Action: Of Structures that 

are passing in Man's Present Evolution 164 

vii 



viii CONTENTS 

CHAPTER XV page 

The Nose 185 

CHAPTER XVI 

The Maxillary Sinuses 203 

CHAPTER XVII 

The Jaws 209 

CHAPTER XVIII 

The Dental Arches 218 

CHAPTER XIX 

The Alveolar Process 224 

CHAPTER XX 

Interstitial Gingivitis 233 

CHAPTER XXI 

Endarteritis Obliterans and Calcic Deposits 249 

CHAPTER XXII 

Pus Infection 259 

CHAPTER XXIII 

The Vault 273 

CHAPTER XXIV 

Cleft Palate and Harelip 292 

CHAPTER XXV 

The Vertebrate Teeth '. 302 

CHAPTER XXVI 

The Phylogeny and Ontogeny of Tooth Development 335 

CHAPTER XXVII 

The Ontogeny of Human Teeth 342 

CHAPTER XXVIII 

The Dental Pulp 375 

CHAPTER XXIX 

The Effects of Pulp Diseases on Tooth Structure 412 



Bibliography 423 

Index. ....... ....... 429 



ILLUSTRATIONS 



CHAPTER I 

FIGURE PAGE 

1. Diagram of a cell (D. Kerfoot Shute) 2 

2. Amoeba proteus (D. Kerfoot Shute) 4 

3. Mitosis (D. Kerfoot Shute) 5 

4. Fertilization of human ovum (D. Kerfoot Shute) 6 

5. Spermatozoa (Landois and Stirling) 7 

6. Segmentation of the fertilized ovum (modified from Shute) 8 

7. Blastodermic vesicle of rabbit (Van Beneden) 9 

8. The Epiblast, Mesoblast and Hypoblast (Van Beneden) 10 

9. Different types of body cells (Animal Studies, Jordan, Kellogg and Heath) 11 

CHAPTER II 

10. Egg of fish, reptile, bird, mammal, (modified from Animal Studies, Jordan, Kellogg 

and Heath) 15 

11. Vertebrate embryos (after Haeckel) 16 

12. Insect development (modified from Animal Studies, Jordan, Kellogg and Heath). 17 

13. Frog development (modified from Animal Studies, Jordan, Kellogg and Heath)... 18 

14. Human Embryology (original) 20 

15. Tree of Life (D. Kerfoot Shute) 22 

16. Skull of man and gorilla (British Museum Guide to Mammalia) 25 

CHAPTER III 

17. Brain of fish (modified from Hertwig's Manual of Zoology, Kingsley) 28 

18. Brain of frog (modified from Hertwig's Manual of Zoology, Kingsley) 28 

19. Brain of bird (modified from Hertwig's Manual of Zoology, Kingsley) 29 

20. Brain of lemur (modified from Shute) 30 

21. Brain of man (Carus's "Soul of Man," by courtesy of The Open Court Publishing 

Co) 31 

22. Diagrammatic Sketch of the phylogeny and ontogeny of the brain (modified from 

Le Count) 32 

23. Brain of the human embryo in its ontogenic development (His) 33 

24. Evolution in phylogeny and ontogeny of the pyramidal cells of the brain (Ramon 

y Cajal) 34 

CHAPTER IV 

25. Diagram of modification of arterial arches in various vertebrate classes (Hertwig's 

Manual of Zoology, Kingsley) 39 

26. Branchial arch changes (Von Baer) .'....' 41 

27. Development of the heart (Landois and Stirling) 43 

CHAPTER VI 

28. Development of the uro-genital system in higher vertebrates (DeMoor) 54 

ix 



x ILLUSTRATIONS 

FIGURE CHAPTER VII p AGE 

29. The amphioxus (Lankester) 59 

30. Embryo of rabbit (Mihalkovics) 60 

31. Chondrocranium of an inscctivoros mammal (W. K. Parker) 60 

32. Cartilaginous skull of shark (Bland Sutton) 62 

33. Skull showing fontanelles (Gray) 62 

34. Lateral view of skull showing wormian bones (Charles A. Parker) 63 

35. Front view of skull showing open suture in center of frontal bone (Charles A. 

Parker) 64 

36. Wild boar contrasted with the modern domesticated pig. (Darwin and after 

, Darwin) 66 

37. Evolution of the face (Camper) 66 

38. Pithecanthropus erectus restored (Dubois) 67 

39. Early embryos (His) 68 

40. Embryos from the fourth to the fifth week (His) ' 69 

41. Fetus showing development of the face and mouth at the 27th day (Piersol's 

Human Anatomy) 69 

42. Embryos from second month (His) 70 

43. Four views of the human skull in its cartilaginous development (Sutton) 71 

44. Skulls in their evolution from the third month to birth (prepared for this work by 

Dr. Charles Ward, Rochester, New York) 73 

45. Skulls in their evolution from birth to three years and six months (prepared for 

this work by Dr. Charles Ward, Rochester, New York) 74 

46. Reconstruction of the face (His) 76 

47. Skull showing the jaws and face on the perpendicular line (original) 80 

48. Dolichocephaly (Greves) 80 

49. Brachycephaly (Greves) 80 

CHAPTER VIII 

50. Fetus, fourth month (original) 87 

51. Prophecy of child development and adult fulfilment (modified from Havelock Ellis) 91 

CHAPTER IX 

52. Developmental stage of man (original) 97 

53. Durencephalous child (original) 99 

54. Fetal brain at six months (Bastain) 100 

55. Normal healthy brain (Carus's "Soul of Man") 101 

56. Brain of the mathematician Gauss (Vogt) 101 

57. Paranoiac criminal brain (Ziegler) 102 

58. Brain of an idiot (Ziegler) 103 

59. Brain of an imbecile (Spitzka) 103 

60. Diagrammatic scheme of the course of the fibers with the brain (Ramon y Cajal) 104 

61. Brain map; specialized function in the cortex cerebri (Dana) 105 

62. Cortical specialized cells of the brain (Dana) 106 

CHAPTER XII 

63 Diagram showing progressive and degenerative evolution of a structure or organ 

(Magnan and Legrain) 131 

64. Durencephalous head of new born child (original) 133 



ILLUSTRATIONS xi 

FIGURE PAGE 

65. Arrest of development of the entire body at eight years of age due to scarlet fever . 133 

66. Figure to left skeleton of female cretinoid dwarf. Figure to right skeleton of 

female dwarf (Ziegler) 134 

67. Skeleton of anthropoid apes and man (Huxley) 135 

68. Evolution of the limbs from the fin (Carnegie Museum) 136 

69. "Pepin" (Gould and Pyle) - 137 

70. Example of siren (Gould and Pyle) 138 

71. Excessive hair growth (Ziegler) 139 

72. "Jo-jo" (Gould and Pyle) 139 

73. Development of the ear (Minot) 141 

74. Elephantine ear (original) 143 

75. The Darwinian ear (Darwin) 143 

76. Anus is absent; rectum ends in the vagina (Ball) 144 

77. Anus is absent; rectum ends in bladder (Ball) 145 

78. Arrest of development of the uterus (Ziegler) 146 

79. Arrest of development of the intestine (Ziegler) 147 

80. Spina-bifida (W. A. Pusey) 148 

81. Caudal appendix observed in a child (Clinic of M. Gosselin, Gould and Pyle) 149 

82. Arrest of the rim of the acetabulum (Ziegler) 150 

83. Flat foot (original) 151 

CHAPTER XIII 

84. Illustration of the grasping power of infants (Photographed by Dr. Louis Robin- 

son) (Shute) 157 

85. Head of lizard or horned toad (W. S. Atkinson) 158 

86. Diagram indicating the progressive evolution and the degeneration of the pineal 

eye (Baldwin Spencer) 159 

87. Human cyclops (original) 160 

88. Skull showing excessive orbital cavities (Greves) 161 

89. The vermiform appendix (original) 162 

90. The vermiform appendix (original) 162 

CHAPTER XIV 

91. Evolution of the face from the anthropoid ape (Camper) 165 

92. Face on the perpendicular line (original) 165 

93. Evolution and degeneration of the face (original) 167 

94. Phylogenic arrest of the face (original) 167 

95. Prognathism (Greves) : 167 

96. Ontogenic antero posterior arrest of the face (original) 168 

97. Skull showing ontogenic arrest of the face (Greves) 168 

98. Ontogenic lateral arrest of the face (original) 169 

99. Skull showing ontogenic lateral arrest of the face (Greves) 169 

100. Phylogenic arrest of the face and upper jaw (Lee Wallace Dean) 170 

101. Skull showing phylogenic arrest of the upper jaw (Greves) 170 

102. Phylogenic arrest of the lower jaw (original) 171 

103. Skull showing phylogenic arrest of the lower jaw (Greves) 171 

104. Head of an idiot girl (Ziegler) 172 

105. Head of a knife grinder (L'Arrotino) 172 

106. Habitual criminal (horsethief) (original) 173 



xii ILLUSTRATIONS 

FIGURE PAGE 

107. Russian harlot (original) 173 

108. A college graduate (egotist) (original) 174 

109. An actress (original) 174 

110. An insane face (original) 175 

111. One sided genius (original) 175 

112. Marked degenerate face, fairly intelligent (original) 176 

113. A kelptomaniac (original) 176 

114. A criminal banker (original) 176 

115. A lawyer (original) 176 

116. An insane criminal (original) 177 

117. A ward politician, an habitual liar (original) 177 

118. A murderer (original) 178 

119. An actor (original) 178 

120. A "smart" business man (original) 178 

121. An "eccentric" business man (original) 178 

122. "Fairly intelligent" business man (original) 179 

123 A successful lawyer (original) 180 

CHAPTER XV 

124. Genus nasalis or proboscis monkey (Library of Natural History, Vol. 1, Sec. 1) . . . 185 

125. Phylogenic arrest of the face, nose and jaws at the snout period (Gould and Pyle) 186 

126. Phylogenic arrest at the snout period (Gould and Pyle) 186 

127. Head of an anthropoid ape (original) 187 

128. Aztec idiot (Gould and Pyle) 187 

129. Excessive nose development (Gould and Pyle) 187 

130. Ontogenic arrest of the nose (original) 188 

131. Ontogenic arrest of the nose and face (original) 189 

132. Arrest in phylogeny of the internal nose (original) 191 

133. Nasal stenosis or arrest in ontogeny (original) 192 

134. Arrest of development of the turbinates (Zuckerkandl) 193 

135. Excessive development of the turbinates (Zuckerkandl) 193 

136. Undeveloped inferior and middle turbinates (Zuckerkandl) 194 

137. Diagrammatic scheme of the nose bones (Casselberry) 195 

138. Break in the septum between the turbinates of the right side and opposite hyper- 

trophied middle turbinate of the left (Zuckerkandl) 196 

139. Separation of the vomer throughout with hypertrophy of the inferior turbinate 

(original) 197 

CHAPTER XVI 

140. .Maxillary sinuses extending close to median line (Zuckerkandl) 203 

141. Arrest of the maxillary sinuses and the nasal cavities extending beyond the alveolar 

process (Zuckerkandl) 204 

142. The nasal cavities developed to the left side of face (Zuckerkandl) 204 

143. Arrest of the right antrum and excessive development of the left (Zuckerkandl) 205 

144. The roots of the teeth extend into the antrum (Zuckerkandl) 206 

CHAPTER XVII 

145. A skull at birth showing arrest of the face and the superior maxilla (Spoldeholtz 

Anantomy) 210 



ILLUSTRATIONS xiii 

FIGURE PAGE 

146. Excessive development of the superior maxilla (original) 211 

147. Excessive development of the lower maxilla (original) 212 

148. Excessive development (hypertrophy) of the superior alveolar process downwards 

(original) 212 

149. A weak upper alveolar process and a strongly developed lower jaw (original) 213 

150. Excessive development of the rami (original) 214 

151. Reverse condition of Figure 150 (original) 214 

152. Arrest of the body of the lower jaw (original) 215 

153. Arrest of the inferior maxilla (V. P. Blair) 215 

154. Complete absence of lower maxilla (Sutton) 215 

CHAPTER XVIII 

155. A normal dental arch (original) ; 218 

156. A V-shaped dental arch (original) 220 

157. A saddle-shaped dental arch (original) 220 

158. A partial V-shaped dental arch (original) 221 

159. A semi V-shaped dental arch (original) 221 

160. A partial saddle-shaped dental arch (original) 222 

161. A semi saddle-shaped dental arch (original) 222 

162. A V and saddle-shaped dental arch combined (original) 222 

CHAPTER XIX 

163. Upper jaw after the teeth have been removed (original) 224 

164. Superior and inferior maxillary bones and teeth with the outer plate of alveolar 

process removed (original) 226 

165. Superior and inferior maxillary bone. Absorption of the alveolar process where 

the teeth have been removed (original) 227 

166. Enlargement of the circle of the alveolar process influenced by the lower teeth (ori- 

ginal) 227 

167. Hypertrophy of the alveolar process throughout (original) 228 

168. Hypertrophy of the alveolar process (original) 228 

169. Hypertrophy of the alveolar process in connection with three left superior molars 

(original) 229 

170. Section of bone showing blood vessels of Von Ebner (Kolliker) 230 

171. Section of bone (higher magnification) showing blood vessels of Von Ebner (Kolli- 

ker) 230 

172. Transverse section of the humerus magnified 350 times (Gray) 231 

173. Longitudinal section of bone magnified 100 times (Gray) 231 

CHAPTER XX 

174. A monkey skull showing absorption of the alveolar process (original) 236 

175. The mouth of a Scotch terrier with loss of teeth due to interstitial gingivitis (origi- 

nal) 237 

176. Teeth of dog removed by fingers due to interstitial gingivitis (original) 238 

177. Cast showing absorption of the alveolar process (original) 239 

178. Cast showing absorption of the alveolar process (original) 239 

179. Microscopic illustration of the first stage of inflammation in jaw of dog (original) . . 240 

180. Four areas of halisteresis absorption in alveolar process of man (original) 241 



xiv ILLUSTRATIONS 

FIGURE PAGE 

181. Two areas of lialisleresis absorption with trabeculac in position filled with round 

cell infiltration (original) 2-12 

1 S l 2. 1 [alisteresis with trabeculae destroyed in center of cavity (original) 243 

183. Halisteresis and Volkmann's perforating canal absorption (original) 243 

184. Lacunar or osteoclast absorption (original) 244 

185. Three forms of bone absorption between bicuspid roots (original) 244 

186. Islands of alveolar process in dog due to two forms of bone absorption (original).. . 245 

187. Cross section of tooth, alveolar process and peridental membrane in man (original) 246 

CHAPTER XXI 

188. Endarteritis obliterans (Kaufman) 250 

189. Endarteritis obliterans, scurvy in man (original) 251 

190. Endarteritis obliterans in pregnancy (original) 252 

191. Endarteritis obliterans in alveolar process of dog (original) 252 

192. Endarteritis obliterans in a tuberculous monkey (original) 253 

193. Endarteritis obliterans in mercurial poisoning (original) 254 

194. Endarteritis obliterans in lead poisoning (original) 255 

195. Endarteritis obliterans in diabetes mellitus (original) 255 

196. Endarteritis obliterans in a syphilitic (original) 256 

197. Calcic deposits from absorbed alveolar process upon the palatine root of a molar 

tooth (original) 257 

CHAPTER XXII 

198. Inflammation of the gum margin (original) 260 

199. Section deeper at the alveolar border (original) 260 

200. Active inflammation in the peridental membrane and trabeculae (original) 261 

201. Violent inflammation in the peridental membrane and trabeculae (original) 261 

202. Shows the root of the tooth, the peridental membrane, active inflammation in the 

trabeculae and the formation of two abscesses (original) 262 

203. Thickening of the peridental membrane and trabeculae (original) 263 

204. The removal of the outer plate of bone and exposing the root of the tooth and 

alveolar abscess (original) 263 

205. Tooth with abscess attached removed from the bone (original) 264 

206. Microscopic illustration of the end of the root of the tooth, abscess attached and 

two points of liquefaction (original) 264 

207. Microscopic alveolar abscess sac (original) 265 

208. Tooth showing formation and destructiou of abscess with carious cavity (original) . 265 

209. Active inflammation of peridental membrane due to mercurial poisoning (original). 266 

210. Breaking down of tissue and the formation of abscess due to mercurial poisoning 

(original) 267 

211. Active inflammation of the peridental membrane and trabeculae due to lead poison- 

ing (original) 268 

212. Four abscesses due to lead poisoning (original) 268 

213. Four abscesses in the peridental membrane and trabeculae in a diabetic man 

(original) 269 

214. Active inflammation in the trabeculae of a scurvy patient (original) 270 

215. Active inflammation around an artery with liquefaction and formation of an 

abscess in same patient (original) 271 



ILLUSTRATIONS xv 

figure CHAPTER XXIII page 

216. Palatometer (original) 274 

217. The casts of jaws of children from two to six years of age (original) 283 

218. Cross section of jaws at the first permanent molar (original) 286 

219. Cast of jaw and teeth of a fifty-year-old man (original) 287 

220. Application of an appliance for opening the suture by spreading the dental arch 

(G. V. I. Brown) 287 

221. The result of spreading the dental arch (G. V. I. Brown) 288 

222. Excessive hypertrophy of the alveolar process producing a deformed vault, natural 

size (original) 288 

223. Excessive development of the alveolar process producing deformity of the vault 

(original) 289 

CHAPTER XXIV 

224. Portion of head of about thirty-four days, showing roof of primitive cavity (His) . . 293 

225. A woman with double harelip (Carpenter) 294 

226. A woman with cleft palate (Carpenter) 295 

CHAPTER XXV 

227. Spines or placoid scales (Hertwig) 302 

228. Transverse section of lower jaw of dog fish (Tomes) 303 

229. Sagittal section of placoid scale (Hofer) 303 

230. Teeth of Port Jackson Shark (original) 304 

231. Upper jaw of Port Jackson Shark (Owen) * 304 

232. Horny tooth of Bdellostoma (Beard) 305 

233. The lower jaw of Sheep 's Head Sargus Ovis (original) 305 

234. The upper jaw of Sheep's Head Sargus Ovis (original) 306 

235. Lower jaw of an eel (Tomes) 306 

236. Hinged tooth of pike (Tomes) 307 

237. Lower jaw of haddock (Tomes) 307 

238. Rostrum and underside of head of small pristis (Tomes) 308 

239. Lower jaw of lizard (Tomes) 309 

240. Section of tooth and portion of jaw of python (Tomes) 310 

241. Jaws of the crocodile (Tomes) 311 

242. Section of premaxillary bone of reptile showing attachment (Hertwig) 312 

243. Section of jaw of young alligator (Tomes) 313 

244. Head of extinct bird, natural size (Dames) 313 

245. Skeleton of Hesperornis regalis (Marsh) 314 

246. Tooth of Hesperornis regalis (Marsh) SI 5 

247. Skeleton of Ichthyomis victor (Marsh) 316 

248. Skull of dog divided down the center to show internal structure (Sir W. H. Flower) 318 

249. The Ornithorhynchus or Australian duck-bill (British Museum Guide to Mammalia) 319 

250. The common Echidna or Ant-eater (British Museum Guide to Mammalia) 319 

251. Mammalian molar forms (Prieswerk) 327 

CHAPTER XXVI 

252. Fir.st appearance of tooth development (Frey) 335 

253. A simple papillae of the mucous membrane (Kolliker) 336 

254. Section of lower jaw of an bovine embryo (Legros & Magitot) 337 



xvi ILLUSTRATIONS 



FIGURE PAGE 

255 Section of upper jaw of kitten at birth (Tomes) 337 

256. Section through the incisive region of lower jaw of human fetus (Legros and Magi- 

tot) 339 

257. Section of lower jaw of bovine embryo (Legros and Magitot) 340 

CHAPTER XXVII 

Plate A. Evolution of human tooth (Osborn) 343 

258. Lower fossil jaw and teeth of animal of Jurassic period (Osborn) 344 

259. Upper jaw of chamelon (Rose) 345 

260. Diagram of eruption and calcification of temporary teeth (Pierce) 346 

261. Diagram of eruption and calcification of permanent teeth (Pierce) 347 

262. Supernumerary permanent incisors (original) 349 

263. Supernumerary temporary lateral incisors (original) 349 

264. Supernumerary lateral incisors (original) 350 

265. Supernumerary centrals, cuspids, bicuspids, and molars (original) 350 

266. Jaws and teeth of Port Jackson Shark (original) 351 

267. Supernumerary permanent third molar (original) 351 

268. Cone-shaped permanent supernumerary teeth (original) 352 

269. Cone-shaped supernumerary third molars (original) 352 

270. Teeth in their evolution (Smale and Colyer) 353 

271. Permanent third molar missing (original) 353 

272. Both third molars missing (original) 354 

273. Permanent laterals missing (original) 354 

274. Cone-shaped teeth (American System of Dentistry) 355 

275. So-called syphilitic teeth (American System of Dentistry) 356 

276. Arrest of development of the upper jaw and bicuspid teeth (original) 356 

277. So-called " Hutchinson " teeth (American System of Dentistry) 357 

278. 279, 280, 281. Show differentiation theory with tendency to conate (Smale and 

Colyer) 357-358 

282. Lower jaw and rotation of biscuspids (original) 358 

283. Lower jaw showing conate teeth (Smale and Colyer) 359 

284. Upper and lower jaw showing conate teeth (Smale and Colyer) 359 

285. Upper jaw showing cusp on cuspid teeth (original) 360 

286. Section of the incisor of horse (Owen) 360 

287. Cast showing cusp on human central (original) 361 

288. Cast showing cusps on first permanent molars (original) 361 

289. Cast showing evolution of the teeth (Smale and Colyer) 362 

290. 291, 292, 293, 294, 295, 296, 297, 298, 299, Deformed teeth demonstrating concres- 

cence theory (Smale and Colyer) 363-366 

300. Malformed crown of third molar tooth (Dental Review) 366 

301. Diagram showing normal position of roots (Dental Review) 367 

302. Phylogenic position of roots (Dental Review) 367 

303. Cast showing serrated teeth (original) 367 

304. Teeth of the Flying Lemur (Owen) 368 

305. Cast of upper jaw showing imbedded cuspid (Salter) 368 

306. Upper jaw of narwhal (Owen) 369 

307. Elongated human molar (American System of Dentistry) 369 

308. Elongated tooth of horse (Tomes) 370 

309. Cast showing tooth roots (American System of Dentistry) 370 



ILLUSTRATIONS xvil 

FIGURE PAGE 

310. Third molar of pithecanthropus erectus (Dubois) 372 

CHAPTER XXVIII 

311. Diagram showing tusk of elephant and the development of the roots of permanent 

teeth (original) 376 

312. Microscopic section of human dental pulp showing so-called lymph spaces (original) 378 

313. Microscopic section of human dental pulp showing so-called lymph spaces (original) 379 

314. Microscopic section of dental pulp showing nerve trunk (original) 380 

315. Microscopic section of dental pulp showing vasomotor system of nerve fibers 

(original) 380 

316. Microscopic section of dental pulp showing arteries and vasomotor system (original) 381 

317. Microscopic section of dental pulp showing arteries and vasomotor system (original) 381 

318. Microscopic section of dental pulp showing arteries and vasomotor system (origi- 

nal) 383 

319. Microscopic section of dental pulp showing arteries and vasomotor system (origi- 

nal) : 383 

320. Microscopic section of dental pulp showing cross section of nerve fibers (original) . . 384 

321. Microscopic section of dental pulp showing distribution of nerves in odontoblastic 

layer (original) 385 

322. Microscopic section of dental pulp showing arteries, nerves and foci of inflamma- 

tion around arteries (original) 387 

323. Microscopic section of dental pulp showing arteries, nerves and foci of inflamma- 

tion around arteries (original) 388 

324. Microscopic section of dental pulp showing round celled infiltration (original) 389 

325. Microscopic section of dental palp showing round celled infiltration further ad- 

vanced (original) 390 

326. Microscopic section of dental pulp showing active inflammation and breaking 

down of tissue (original) 391 

327. Microscopic section of dental pulp showing active inflammation and breaking down 

of tissue further advanced (original) 392 

328. Microscopic section of dental pulp, showing active inflammation and breaking 

down of tissue, formation of abscess (original) 393 

329. Microscopic section of dental pulp showing active inflammation and breaking 

down of tissue, formation of abscess at apical end of root (original) 394 

330. Microscopic section of dental pulp showing round cell inflammation, abscess and 

healed abscess (original) 395 

331. Diagrammatic illustration of a healthy nerve and nerve degeneration (Ziegler) .... 396 

332. Microscopic section of dental pulp showing nerve end degeneration (original) 397 

333. 334. 335. Microscopic section of dental pulp showing nerve end degeneration 

(original) 398-400 

336. Microscopic section of dental pulp showing thrombosis of the capillaries (original) . 401 

337. Microscopic section of dental pulp showing dilated vessels, diapedesis and embol- 

ism (original) 402 

338. Microscopic section of dental pulp showing endarteritis obliterans (original) .... 403 

339. Microscopic section of dental pulp showing enlarged artery in early stages of 

thickening (original) 404 

340. Microscopic section of dental pulp showing pulp stones (original) 405 

341. Microscopic section of dental pulp showing fatty degeneration (original) 406 



xviii ILLUSTRATIONS 



FIGURE PAGE 

342. Microscopic section of dental pulp showing dilated vessels, amyloid deposits and 

pulp stones (original) 407 

343. Microscopic section of dental pulp showing calcic deposits and enlarged blood 

vessels (original) 408 

344. Microscopic section of dental pulp showing nerve fibres, internodes, axis cylinders. 

myalin degeneration (origiginal) 409 

345. Microscopic section of dental pulp showing medullary nerve fibres slightlythickened 

and degeneration of connective tissue (original) 410 

346. Microscopic section of dental pulp showing interstitial fibrosis and acute inflamma- 

tion cells (original) 411 



INTRODUCTION 

DEVELOPMENTAL pathology, while rather extensively considered 
in surgery, in the domain of tumors, of orthopedics, and also in 
connection with abnormalities of the liver and also of the bones 
so far as cervical ribs are concerned, has not received the attention which 
its relations to the etiologic moment of disease and disorder merit. The 
congenital states "and their post-congenital possibilities are, to a very 
limited degree, recognized in the embryonic and reversionary explanations 
of cancer and malignant growth. To a still more limited degree, develop- 
mental pathology is recognized in hematology, since pernicious anaemia is,, 
by leading pathologists, considered a reversion to embryogenic bud states. 
The alienists have long regarded many of the psychoses as expressions of 
arrests of cerebral development or of its post-congenital possibilities. The 
same is true of the so-called hereditary neuroses and psychoses. The 
other organ states have been less regarded, although both the gynecologists 
and the genito-urinary surgeons have shown tendencies to take the develop- 
mental pathology of these into account in dealing with the origin and 
consequences of morbid conditions. 

The two great phases of developmental pathology have, however, 
not been used to the degree they should be as guides in the analysis of 
symptoms and consequences. While conditions in reversion have been 
considered to some extent, those occurring in phylogeny (race development) 
have not been separated from those occurring in ontogeny (development 
of the individual man). Ontogeny does not repeat all the steps of phylo- 
geny, but assumes the essential characters of the race rather quickly. Very 
frequently the lower phases of phylogeny are, therefore, represented by 
potentialities capable of development, rather than by the structures them- 
selves. 

Developmental pathology, then, may be regarded as the domain of 
pathology which deals with departures of structures and organs from the 
normal along the line of arrests of fetal evolution, either in structure or 
in the biochemic states underlying functions or potentialities of develop- 
ment at given periods of growth. Atrophies, with or without resultant 
hypertrophies, and vice versa are underlain by its laws. 

The general trend has resulted in a working hypothesis compatible 
with all pathologic phenomena of all the structures of the body, but more 
especially of the head, face, nose, jaws and teeth, since they are more easily 
recognized. With this as a guide, the student can readily study the 
pathologic details of any structure of the body. 

To comprehend the pathology of these structures, the laws of phylo- 
geny must be understood. Phylogeny is that process by which an individ- 

xix 



xx INTRODUCTION 

ual or structure is transformed from a lower to a higher type. Man is 
still undergoing evolution. His structures are continually changing to 
suit environment. The master hand is adding a little here and taking 
away a little there, to adjust him to new conditions as they arise in the 
world. This process, which has been going on ever since man appeared, 
is still in progress. 

Degeneration is a gradual decline of the structure in type. While 
the changes pertaining to evolution are in progress, man suffers more or 
less from his ignorance of the laws governing them, the proper under- 
standing and strict observance of which would banish disease from the 
earth. His ignorance and consequent failure to re-adjust himself to 
changing conditions, clog the wheels of evolutional progress and bring 
about suffering and misery. Not only so, but during the progress of 
evolutional changes, various extrinsic obstacles are placed in his way, 
which not only hinder progress but cause degeneration, in type, of his 
structures. These obstacles consist in parental excesses, resulting in 
neurasthenia, intrauterine infections from parent to fetus and eruptive 
diseases of the child. 

In man's ontogeny, phylogeny and degeneration go hand in hand. 
An organ or structure remains with man if, and so long as, it develops or 
aids in the formation of a new organ. The brain is an apt illustration. 
Degeneration of an organ or group of organs consists in a gradual restric- 
tion or disuse of structures, and their final obliteration or disappearance. 
The muscles of the ear, the vermiform appendix, the little toe, the false 
ribs, the pineal eye, and especially the face, including the nose, jaw T s and 
teeth, are peculiarly involved in this process. 

Progression can take place in the struggle for existence only through 
general development at the expense of disused organs. The structures 
of man are influenced greatly by environment. If he remains in a savage 
condition, generation after generation, his surroundings being the same, 
he will retain, as a rule, certain fixed conditions of structure. Thus, his 
brain will not develop, but owing to the retention of the primitive use of 
his jaws in masticating coarse food, etc., these will retain the size and 
strength of primitive life. On the other hand, if he abandon the savage 
life, develop his brain, and is not forced to masticate food, his jaws and 
teeth atrophy. A marked example of this theory in this country is the 
evolution of the negro in the past two hundred and fifty years from a 
dolichocephalic to a mesaticephalic head, and from a prognathous to an 
orthognathous jaw. Man, in his development from the lowest vertebrate, 
passes through all the vertebrate stages from the fish and reptile to bird 
and mammal. 

This phraseology is used throughout the entire work, since it simplifies 



INTRODUCTION xxi 

and makes clear the various stages of man's development. This, however, 
is not strictly scientific. The terms ichthyopsidae, sauropsidae and 
mammal are more to the point, for the reason that the terms denote clearly 
the relationship resultant on the place in the scale of life. The bird, for 
example, while related in physiology to the mammal, is otherwise an aber- 
rant reptile. Bird and mammal evolve from the generalized type conveyed 
by the term sauropsidae and not from each other as ordinary phraseology 
implies. Human embryologic relationships are to the generalized type, 
not to either bird or reptile. Lower in embryogeny, human type is related 
to the generalized type, ichthyopsidae, not to either specialized fish or 
specialized frog. 

In his flight from cell to fully developed compound animal, man at 
the present period of his evolution has, as a result of a loss in explosive 
force, developed a nervous system. How well he accomplishes this develop- 
ment depends upon brain health. The brain of man develops first, to 
preside over the development of the other structures. If the brain be 
normal the structures of the body will develop normal; on the other hand, 
if from any cause the brain is abnormally developed, unstable or defective, 
the structures of the body become abnormal. When arrests of the brain 
occur different classes of degenerates result. 

The structures of the nose and cavities of the face display much 
abnormality because of excessive and arrested development due to their 
transitory nature and to an unstable nervous system. 

In the development of man from the primitive cell, periods of stress 
constituting new environment occur. Those which occur during develop- 
ment are called periods of evolution, and those after maturity, periods of 
involution. At these periods of stress, development of the nervous system 
may be strained, producing arrests of development or degeneration. 

Structures undergoing arrests or degenerations are, because of lessened 
blood supply, more liable to disease than structures which are evolving 
higher. Marked illustrations of this may be found in irregularities of the 
teeth and disharmony in jaw development where the teeth are not being 
lost fast enough for the receding jaws. Interstitial gingivitis and decay 
are natural methods of hastening the process. 

Arrests which occur at any period along the line of development 
account for all the so-called deformities of the body, which are reversions 
simulating some features of the lower animals, characteristic of fetal 
stages through which man has passed. No structures of the body are so 
prone to these arrests or degenerations as the face, nose, jaws, and teeth, 
since they are continuous in the line of evolution and are governed by the 
law of economy of growth in the struggle for existence between organs. 
This struggle for existence between organs takes place among the animals 



xxii INTRODUCTION 

as well as man. Wild animals in captivity and other animals through 
domestication (change of environment and food) have changes in struc- 
tures similar to that of man. 

States normal in lower animals have become abnormal in man. This 
is of necessity modified by the increasing complexity of ontogeny or individ- 
ual development in man as affecting phylogeny or race development. 
Not only are structures affected by these elements, but functions are like- 
wise so modified without underlying structural change. Uric acid excre- 
tion, for example, normal in the sauropsidae (birds and reptiles) has become 
abnormal in man. Its secretion by mammals is, as Fothergill shows, an 
abnormality with serious consequences. What is true of uric acid is 
likewise true of other products of suboxidation and imperfect elimination, 
like indican and excessive acid. The presence of these clogs, like clinkers, 
the working of the structures, and acts in a peculiar vicious circle to increase 
the conditions which produce them. 



DEVELOPMENTAL PATHOLOGY 

A STUDY IN DEGENERATIVE EVOLUTION 

Chapter I 

NATURE OF LIVING BEINGS 

Cells 

THE bodies of living beings are made up of small particles of living 
matter called cells, together with a variable amount of non-living 
matter. The non-living matter comprises either the particles 
which are cast from the living cells as a result of their activity and those 
particles which have been taken into the body to further the cell activity. 
The activities of the living matter, which distinguish it from non- 
living matter, may be summed up as follows: 

1. Living matter is able to take from its surroundings non-living 
matter and change it so as to serve its own needs. 

2. Some of this matter it transforms, so that it possesses the proper- 
ties of living matter. The matter is then said to be assimilated. The 
activities of a cell are attended by a destruction of its substance. The 
assimilated matter serves to replace that which is destroyed in consequence 
of cell activity. If the matter assimilated exceeds that destroyed, the 
amount of living matter increases and the cell grows. 

3. The cell, having arrived at a certain age or size, is able to give rise 
to Jiew cells by a process termed reproduction. 

4. The cell exhibits the phenomena of spontaneous movement. 

5. It is excitable (reacts to stimuli). 

6. It gives off heat. 

In some species, the individual organism consists of a single cell, 
which in itself is a complete and perfect organism. Such a cell has the 
various powers of assimilation, of protecting itself against the external 
world, and of reproducing its kind, developed to an equal degree. Such 
organisms are said to be unicellular. 

Other organisms consist of many cells grouped together. Of this class 
of organisms, some are of so simple a structure that there appears to be 
no difference of form or function between the different cells. On the other 
hand, the conditions for the chemical changes necessary to the digestion 

1 



■2 DEVELOPMENTAL PATHOLOGY 

■of food are more favorable in the interior of the organism, and thus the 
higher animals and plants come to be composed of differentiated cells that 
have developed, some one function, some another, to a high degree, while 
holding the other functions in relative abeyance. A sort of economy of 
effort, a division of labor is thus set up. Such organisms are organized 
multicellular beings. They are not haphazard collections of cells, but in 
each individual the various groups of cells constitute a single organ in 
which the functions of the various cells are highly specialized, and all are 
under the control of a single governing power which moderates or stimu- 
lates the actions of each cell, co-ordinating them in such a way as to secure 
the welfare of the organism as a whole. 

In such a differentiated organism, the power of the individual cells 
to move is greatly restricted, and none of them is able, for more than a short 
time, to maintain existence apart from the other cells of the body. In 
nearly all the cells, the power of reproduction is greatly limited. One 
class of cells, however, possesses the power, under proper circumstances, 
of reproducing the entire body. These are the germ cells of the male and 
female respectively. 



Structure of the Cell 
With the low power of the microscope, three parts of the cell (Fig. 1) 

ATTiacficm Splnete, enclosing a centto&ome 



Nad 



eus 



NucleaiMeirb, 




f Nucleolus^ /KL^^^^/P^&tids 
C^omatt«s^)4i^O^^^Aj^^CeU Wall 
ACToma^n^r^^ M tf^|g^L).| yo [ op \ a&w 



ponqioplc&i 



Vacuole — ^^S^^^MflfoflaSi 



Figure 1 
Diagram of a cell highly magnified (Shute). 

can be distinguished; an outer part, more dense than the interior, some- 
times sharply differentiated as a cell wall; an intermediate portion, known 
as protoplasm; and a central body, called the nucleus. With a somewhat 
higher magnification, a smaller body is seen inside the nucleus, which is 
known as the nucleolus. 

When carefully examined, the structure of the cell is found to be much 
more complex. The protoplasm contains numerous small bodies which 
are known as plastids, and believed by some to be the true physiologic 



A STUDY IN DEGENERATIVE EVOLUTION 3 

units. The protoplasm itself possesses a spongy structure known as 
spongioplasm, the meshes of which are filled with a fluid called hyaloplasm. 

The Nucleus likewise exhibits a complicated structure. Near one 
side is a body known as the centrosome, from which radiate strands con- 
stituting the centrosphere. The nucleus also contains a smaller body 
called the nucleolus. Chemically, the nucleus is found to consist of two 
substances — chromatin, so-called because it is colored by certain stains, 
and linin or achromatin, which is not colored by staining agents. The 
chromatin is closely associated with another non-staining substance known 
as plastin. 

In tissue cells, the nucleoli consist only of plastin. The centrosome 
is often indistinguishable, but is always present and appears to be specially 
related to the function of division of the cells (mitosis). 

The nucleus is the controlling and vivifying part of the cell. While 
the proptoplasm, separated from the nucleus, may exhibit for a time the 
peculiar properties of living matter, it is incapable of continued existence. 
It soon ceases to live and becomes subject to decay and decomposition. 

The Function of the Nucleus includes not only the control of 
nutrition, but also the processes of reproduction. From what we have 
learned of the preparation of the chromatin in the maturation of the ovum 
and sperm, it has been assumed that the chromatin threads are not only 
the active factors in the development of the embryo, but are also the bearers 
of the hereditary tendencies of the cell. Through the germ cells are 
transmitted the accumulated experiences of the race, as shown in the 
development of the different tissues, and in the continuation of those 
peculiarities known as heredity and instinct. 

The Development of the Human Body from a new cell produced 
by the union of the male sperm cell with the female ovum is a process of 
evolution consisting in continued multiplication and differentiation of 
the cells into tissues and organs. The changes thus effected form a con- 
tinuous process, intelligently directed to the formation of a human body 
similar to that from which the original cells sprang. It is believed by 
most biologists that this individual evolution is merely a repetition of the 
series of changes through which the race has passed in its evolution from 
a remote unicellular ancestor, through vertebrate forms, from fish to 
reptile, and from bird to mammal, up to its present status. 

Division of Cells 

The simplest process of reproduction is by the sheer division of a cell 
into two or more similar cells. It is in this way that the tissues grow, and 
this is the most frequent method of reproduction among the simplest 



4 DEVELOPMENTAL PATHOLOGY 

forms of animals. The usual mode of division of cells is known as mitosis. 
In this process, the first event is the migration of the centrosome into the 
protoplasm where it takes up a position close to the nuclear wall. The 
centrosome then divides into two new bodies, which separate so as to be 
at opposite sides of the nucleus. The chromatin cords arrange them- 
selves in the form of a spindle, with the two new centrosomes at the respec- 
tive poles. The chromosomes then divide into double their original 
number, half attaching themselves to one centrosome and half to the 
other, and these sets separate so that two new nuclei are formed. Mean- 
while, the protoplasm separates into two parts corresponding to the new 
nuclei and the formation of two new cells is completed. This process may 
be repeated again and again, so that a large number of cells are formed 
from a single parent. 

Cells may also reproduce themselves by budding, a process essentially 
similar to that of mitosis, except that, instead of the chromatin spindle 
formed in indirect or mitotic division, the nuclear fragments are separated, 
as is the cytoplasm, by simple fission. 

Independent Activity in a unicellular organism is well illustrated 
by the amoeba, (Fig. 2), a creature representative of the simplest form of 




Figure 2 

Amoeba proteus (Shute). n, nucleus; c v, contractile vesicle; e c, ectoplasm; 

e n, endoplasm; p, pseudopodia. 

animal life. It is composed solely of naked protoplasm. Its outer, firmer 
and transparent portion is known as the ectoplasm (ec), while the inner 
(which is granular and more fluid) is called the endoplasm (en). As the 
animal changes its shape, these inner particles or endoplasm move and 
graduate, without apparent union, into the ectoplasm. 

On the outer edge of the endoplasm and attached to the inner surface 
of the ectoplasm, a nucleus (n) can be more or less distinctly seen. It has 



A STUDY IN DEGENERATIVE EVOLUTION 5 

the appearance of a bladder-like cavity surrounding a globular nucleolus. 
A contractile vacuole (cv) is also located in the endoplasm. The animal 
thrusts out projections called pseudopodia or false feet, which sometimes 
consist of ectoplasm, but oftentimes the endoplasm is extended into it so 
that granules can be seen moving from the center into the false feet and 
vice versa. In this manner, the animal's locomotion is performed as a 
sort of creeping. Thus the Amoeba finds those other one-celled Desmids 
and Diatoms upon which it feeds. The Amoeba approaches its food, and 
by means of its pseudopodial movement, flows around and encloses its 
prey within its protoplasm where assimilation takes place. The indigesti- 
ble portions are then cast off. No apparent break can be found in the 
ectoplasm after the animal has forced its prey through it. This action is 
analogous to that of the leucocytes in destroying the poisons in the blood. 
This little creature is found in ponds and streams during the summer 
months. When resting, it is nearly round, but in motion it is flat upon 
one side, while the other is extended. There is no egg stage. Reproduction 
is accomplished by a mitosis (Fig. 3), hence a new Amoeba is like the full 
grown parent, except as to size. 




Figure 3 
Diagram illustrating mitosis (Shute). A, the cell commencing activity; B, C, D, phases in 
the formation of the spindle and chromatin loops or V's, also showing that the mother 
V's have split into daughter V's; D, the chromatin loops forming the equatorial plate, 
chr; E, F, G, separation of the daughter loops (daughter chromosomes) and their passage 
towards the poles of the spindle, thus forming daughter nuclei; H, I, division of the 
protoplasm so as to form two daughter cells; at, attraction sphere enclosing a centro- 
some; n m, nuclear membrane; chr, chromatin threads; p, protoplasm; c w, cell wall; 
sp, spindle. 



6 DEVELOPMENTAL PATHOLOGY 

The Human Ovum 

All the cells of the human body are produced by the repeated sub- 
division and differentiation of the germ cells from which the individual 
takes its origin. 

The Human Ovum is typically multicellular, small (about one-fifth 
of a millimeter in diameter) and globular. It is formed within the female 
sexual gland, or ovary, where it passes through all stages of development, 
from the imperfect progressive changes of its early condition to a partially 
complete maturation, before being liberated. It is enclosed in a protecting 
sac of thin membrane called the zona pellucida. The ovum consists of 
three substances, the yolk or vitellus, a partially fluid protoplasm, an 
active protoplasm or ooplasm, and the nutritive portion or deutoplasm. 
The full formation of the ovum is accomplished by throwing out one part 
of the chromosomes. To accomplish this, the maternal nucleus approaches 
the protoplastic peripheral surface (Fig 4 A) loses its limiting membrane, 
and by mitotic division two daughter nuclei appear, known as the polar 




Figure 4 
Diagram illustrating the maturation and fertilization of the human ovum (Shute). A, one 
polar body is formed and a second is in process of formation; B, both polar bodies are 
formed and a spermatozoid is penetrating the ovum; C and D represent the approach 
of the male pronucleus towards the female pronucleus; E, indicates the amalgamation 
of the two pronuclei to form the nucleus of the oosperm (segmentation nucleus); pol. 
b, polar bodies; pol. c, centrosome of the polar body; chr. p, chromatin of the polar 
body: / pr, female pronucleus; p, protoplasm; p p, peripheral protoplasm (but not cell 
wall) ; / c, female centrosome; m c, male centrosome; m pr, male pronucleus; n, os, nucleus 
of the oosperm (first stage of a human being). 



A STUDY IN DEGENERATIVE EVOLUTION 7 

bodies, Fig. 4 A. B. pol. b. These bodies are seen as small deeply stained 
cells in the space under the zona pellucida. 

The remaining cellular material, after the formation of the polar 
bodies, is gathered within a new nucleus, leaning toward the center within 
the egg, and is called the female pronucleus or egg nucleus. Fig. 4 B. f. pr. 
This nucleus differs from the nucleus of all other body cells in that it only 
contains half as many chromosomes (hereditary threads). 

The flagellate sexual cell of the male, or spermatozoon, corresponds 
to the female ovum. It also contains only half the number of chromo- 
somes. 

Fertilization 



Fertilization is the union of the male and female elements by 
the penetration of the former into the latter. Impregnation takes place 
usually in the upper third of the oviduct, but any part of the genital tract 
may become the site of the union. 

Spermatozoa consist of three parts, head, tail and intermediate 
portion, and are not unlike a tadpole in appearance, Fig. 5. The head, 
triangular and flat from side to side, contains a certain amount of chroma- 
tin. By virtue of the rapid movement of their tails, spermatozoa, accord- 
ing to Henle, can travel one centimeter in three minutes. 




Figure 5 
Spermatozoa (Landois and Stirling). 1, human (X 600), the head seen from the side; 2, on 
edge; k, head; m, middle piece;/, tail; e, terminal filament; 3, from the mouse; 4, both- 
riocephalus latus; 5, deer; 6, mole; 7, green woodpecker; 8, black swan; 9, from a cross 
between a goldfinch (M) and a canary (F) ; 10, from cobitis. 

Normal Human Impregnation is accomplished by a single seminal 
element, Fig. 4 B. s. After the penetration of the ovum by a single male 



8 



DEVELOPMENTAL PATHOLOGY 



element, the vitelline membrane immediately thickens to prevent the 
entrance of additional spermatozoa. The two pronuclei then form a single 
nucleus, Fig. 4 E. n. os. 

The head of the spermatozoon alone enters the ovum; the tail, failing 
to penetrate the vitelline membrane, is soon lost. Thus nothing remains 
of the sperm but a small spindle-shaped mass, the male pronucleus, which 
soon makes its way to the center of the ovum and fuses with the female 
pronucleus to form the segmentation nucleus. The fertilized ovum, or 
oosperm, now contains the normal amount of chromosome material, the 




Figure 6 
Early stages of segmentation of *the primitive cell (Van Beneden). 1, the fertilized ovum; 
2, two segmentation spheres of equal size; 3, the segmentation of the two cells into four; 
4, the four cells divided into eight; 5, the morula stage; 6, section through blastula 
showing a single layer of cells surrounding segmentation cavity; 7, beginning of invagi- 
nation of entoblastic area; 8, complete gastrula. The inner layer (hypoblast), the 
outer layer (epiblast), the opening represents the mouth of the cavity. 



number of chromosomes dimished by the loss of the polar bodies being 
now made up by the addition of the male pronucleus. 

The cell produced by this union is the first existing stage of man, who 
begins his life cycle as a unicellular animal. 



A STUDY IN DEGENERATIVE EVOLUTION 9 

Segmentation of the Ovum 

The result of the union of the male and female pronuclei is the forma- 
tion of a nucleus which, undergoing division by mitosis, forms two cells. 
These in turn divide into four, and so on, until a large mass of small cells 
is formed (Fig. 6), spherical in shape, those near the surface projecting in 
such a manner as to resemble the mulberry or morula, Fig. 6, No. 5. In 
this stage, man is analogous to the protozoans. As growth proceeds, the 
morula cells arrange themselves in a regular layer at the periphery so that 
the embryo is not unlike a hollow sphere. This is termed the blastula 
stage, Fig. 6, No. 6. The next stage in development varies in different 
animals. In some animals, the blastula is found pushed in on one side, 
Fig. 6, No. 7. Typical gastrulation of the lower animals does not occur 
in the higher mammals. The fluid surrounding the morula mass forces 
the cells to the periphery, giving rise to a vesicular structure consisting 




Figure 7 
Blastodermic vesicle of rabbit (Van Beneden). The upper dotted line represents the zona 
pellucida. The line below, the primitive ectoderm; below this, the internal cell mass. 
The space, the cavity of vesicle. The lower line, albuminous envelope. 

of a single layer of cells, which surrounds the cavity filled with fluid, the 
segmentation cavity. This is called the blastodermic vesicle, Fig. 7, which 
has been demonstrated by Beneden in the rabbit. The formation of the 
blastodermic vesicle has not been observed in the human ovum. Since, 
however, it has been demonstrated in the ova of many animals, there is 
little doubt that it is the method of formation of cells in the ova of all 
mammals. This process of cell division is known as segmentation and it 
is common to all animals and plants. 

The nutritive yolk elements of human and mammalian ova are scanty 
but uniformly distributed throughout the vitellus. This uniform distri- 



10 



DEVELOPMENTAL PATHOLOGY 



hut ion is known as homolecithal. In fish, reptiles and birds, on the other 
hand, the yolk is not uniformly distributed, but is collected at one pole. 
This type of segmentation is known as telolecthal. 

Differentiation of Cells 

In many cells, the protoplasm, or the exterior of the cells, contains 
peculiar substances, formed from the protoplasm, which are called 
metaplasm. These substances vary in different cases and lead to the 
differentiation of the cells. The collection of cells of one kind into a con- 
tiguous grouping leads to the formation of tissues, the methodical ar- 
rangement of which results in the purposeful production of organs and of 
the skeletal structure. 

The earliest division of the cells is into three germinal layers (Fig. 8), 
the epiblast (ectoderm), the hypoblast (endoderm) and mesoblast (meso- 




FlGURE 8 

Transverse section through the embryonic disk of a rabbit (Van Beneden). ch, chorda 
endoderm; ee, ectoderm; en, endoderm; gm, gastral mesoderm. 

derm). The cells of the epiblast form a superficial layer known as epithe- 
lium, as a result of many and complicated embryonal infoldings. Other 
cells of the epiblast become entirely enclosed in the interior of the body 
and form the brain, the spinal cord and nerves. 

The Hypoblast also consists of epithelium which lines the digestive 
and respiratory tracts. Some of the epithelium, both of the epiblast and 
the hypoblast, sinks below the surface, still retaining a communication 
with the exterior and forms glandular epithelium (Fig 9.) 

The simplest epithelium is that which serves for the protection of the 
body, the stratified squamous type, the outer layers of which become 
degenerated, flattened, hardened and scale-like and thus form a more or 
less protective armour for the more delicate underlying tissues. From 
such epithelium are developed the appendages (the hair, nails, teeth, 
horns, hoofs, feathers, etc.). In the cavities of the body which communi- 
cate with the exterior, as the mouth, nostrils, external genitalia, etc., the 



A STUDY IN DEGENERATIVE EVOLUTION 



11 



protective epithelium produces mucus which serves to moisten the surfaces 
and carry away injurious substances. The epithelium of the air passages 
is provided with hair-like moving appendages called ciliae, which, with a 
rythmic, wave-like motion, serve to bring foreign bodies to the surface. 
Glands possess a specialized epithelium whose function it is to secrete the 
so-called enzymes, or digestive juices and fluids, necessary for the prepara- 
tion and assimilation of food, and for the economy of the body. 

Specialized epithelium in the skin, the so-called sensory end-organs, 
becomes connected with nerve fibres and serves for the transmission of 
sensory impressions of pressure, pain, heat and cold. 




Figure 9 
Different types of cells composing the body of a highly developed animal (Animal Studies, 
Jordan, Kellogg and Heath). A, cell; /, food materials; n, nucleus; B, blood cell; C, 
nerve cell; with small part of its fiber; D, muscle fiber; E, cells lining the body 
cavity; F, lining of the windpipe; G, section through the skin. Highly magnified. 



The cells of the nervous system are highly differentiated and serve 
for the transmission of impulses of both a sensory and a motor character. 
Each cell possesses long processes which arborize with the processes of 
other distant cells and so form a union by which impulses are relayed from 
the periphery to the higher centers and from the higher centers back to 
the periphery. 

The Mesoblastic cells are modified in various ways. The simplest 
form is the connective tissue cells, long fibres of metaplasm, which are 
woven into membranes, tendons, the sheaths of muscles and the supporting 



12 DEVELOPMENTAL PATHOLOGY 

structure of the various organs. In many parts of the body, these cells 
become filled with fat, giving rise to the adipose tissue. Other cells of the 
mesoblastic layer give rise to a peculiar metaplastic matrix cartilage, in 
which they lie scattered here and there. Moreover, this cartilage may 
become further differentiated, take on osteoblasts, become impregnated 
with lime salts, and form bone. Another peculiar production is the forma- 
tion of layers of protoplasmic material containing hemoglobin and albumi- 
nous substance, known as myosin. These structures constitute the 
striated, or voluntary, and the unstriated, or involuntary, muscles, and 
are under the direct control of the central nervous system through their 
nervous connections. In the bone marrow and the blood vessels the cells 
remain free, and some of them, containing hemoglobin, lose their nuclei 
and serve for the conveyance of oxygen. The others remain colorless and 
retain their nuclei and are known as the leucocytes, or white blood corpus- 
cles. 

In the human body, the white cells of the blood act as unicellullar 
organisms. They possess the power of movement and some of them are 
capable of seizing, engulfing and digesting foreign bodies, such as bacteria, 
in a manner similar to that of Amoeba Proteus. As a further illustration 
of the capabilities of cells in the body, we may refer to the action of the 
osteoblasts and osteoclasts. These cells are naked pieces of protoplasm, 
the osteoclasts being much the larger of the two. The osteoblasts and 
osteoclasts have to do with some of the most interesting phenomena of 
many growing animals. The osteoblasts have the power of constructing 
the bones of animals in the same way as the foraminifera have the power 
of forming complex aggregations of limestone shells. 

The Osteoblasts are bone formers, and the osteoclasts are bone 
destroyers. It is a striking fact that these small specks of living jelly, 
the osteoclasts, should have the power of destroying hard tissue like bone. 
They have power, by virtue of their wonderful chemical processes, to liquefy 
and absorb, and by these means destroy ivory pegs that are driven into 
living bone. The osteoclasts are the agents which destroy the roots of 
the teeth so that the crowns of the temporary teeth are shed and the way 
paved for the appearance of the permanent teeth. The growth and 
shedding of the antlers of the deer furnish a good example of the wonderful 
activity of these little osteoblasts and osteoclasts. While these antlers 
are growing they are covered with a delicate skin, technically called "vel- 
vet." The blood circulating through it keeps this velvet warm and 
sensitive. The blood contains thousands of living osteoblasts that are 
working together under some mysterious directing or co-ordinating agency, 
to build up these splendid beams, tynes and snags that compose the antlers. 
The building of the antlers by these little agents continues through the 



A STUDY IN DEGENERATIVE EVOLUTION 13 

spring and summer. In the fall, the osteoblasts cease their activity and 
die; the delicate, sensitive velvet dries and peels off, leaving the dead, hard 
bony substance exposed and the horns then become weapons for fighting. 
At this season, the stags challenge one another to single combat, the hind 
standing timidly by to be taken by the victor as his mate. After the loves 
and battles of fall are over, and the antlers are no longer of use, they are 
shed. This shedding is brought about by means of the bone destroyers, 
or jelly-like cells, called osteoclasts. 

While man and animals differ in the mode of gastrulation, the common 
point essential to all is the formation of a double cellular membrane. 
These membranes, which are derived from the early blastodermic vesicle, 
are the outer, called the epiblast or ectoderm, and the inner, the hypoblast 
or endoderm. These two are the primary germinal layers; a little later 
a third layer is added between them, known as the mesoblast. These three 
cellular membranes are the base of all the complex human tissues and 
organs. 

The following tissues of the body are derived from each of these 
blastodermic layers: — 

From the Epiblast — The epithelium of the outer surface of the body, 
including that of the conjunctiva and anterior surface of the cornae, the 
external auditory canal, together with the epithelial appendages of the 
skin, as hair, nails, sebaceous and sweat glands (including the involuntary 
muscle of the latter). The epithelium of the nasal tract, with its glands, 
as well as of the cavities communicating therewith. The epithelium of 
the mouth and of the salivary and other glands opening into the oral 
cavity. The enamel of the teeth. The tissues of the nervous system. 
The retina; the crystalline lens and, perhaps, part of the vitreous humor. 
The epithelium of the membraneous labyrinth. The epithelium of the 
pituitary and pineal bodies. 

From the Mesoblast — The connective tissues, including areolar 
tissue, tendon, cartilage, bone, dentine of the teeth. The muscular tissues, 
except that of the sweat-glands and dilator pupillae. The tissues of the 
vascular and lymphatic systems, including their endothelium and circula- 
ting cells. The sexual glands and their excretory passages, as far as the 
termination of the ejaculatory ducts and vagina. The kidney and ureter. 

From the Hypoblast — The epithelium of the digestive tract with 
that of all glandular appendages, except those portions derived from 
epiblastic origin at the beginning (oral cavity) and termination of the tube. 
The epithelium of the respiratory tract. The epithelium of the urinary 
bladder and urethra. The epithelium of the thyroid and thymus bodies, 
the atrophic primary epithelium of the latter being represented by Hassall 's 
corpuscles. 



14 DEVELOPMENTAL PATHOLOGY 

Summary 

Livings beings are made up of cells possessing the powers of (a) meta- 
bolism; (b) assimilation and growth; (c) reproduction; (d) spontaneous 
movement; (e) excitability; (f) heat production. Organisms may be, 1. 
unicellular; 2. multicellular but undifferentiated; 3. multicellular and 
differentiated. 

Structure of the Cell. The cell consists of (a) cell wall; (b) pro- 
toplasm containing, 1, plastids and itself consisting of 2, spongioplasm and 
3, hyaloplasm; (c) nucleus containing 1, centrosome; 2, chromatin beads 
on 3, linin threads (the bearers of hereditary tendencies), and 4, nucleolus 
consisting only of plastin. Functions of the nucleus are (a) control of 
nutrition, and (b) of reproduction. Evolution of the cell proceeds by 
multiplication and differentiation into specialized cells whose arrangement 
forms the various tissues and organs. 

Process of Mitosis. Migration of centrosome. Division into 
polar bodies. Doubling of chromosomes. Separation of chromosomes 
and attachment to two centrosomes with formation of two new nuclei. Divi- 
sion of protoplasm forming two new cells. Cells also multiply by budding. 

The amoeba is a typical unicellular organism consisting of ectoplasm, 
endoplasm, nucleus, vacuole and pseudopodia. 

The Human Ovum consists of a cell which has undergone partial 
mitosis, having cast off half of its chromosomes. The spermatozoon is a 
flagellate cell also containing only half the regular number of chromosomes. 
Fertilization takes place by the penetration of the spermatozoon into the 
ovum with a union of the two pronuclei to form a single nucleus. 

Segmentation of the Ovum results in morula and gastrula-like forms 
which eventually become modified so as to form two primary germinal 
layers, the epiblast and the hypoblast, between which is developed a third 
layer, the mesoblast. From these three layers, by further differentiation 
and segregation, are derived the various tissues, namely, epithelium, 
nerve-cells, connective tissue, cartilage, bone cells, muscle fibres, endothe- 
lium, blood cells, osteoblasts (bone builders) and osteoclasts (bone destroy- 
ers). Out of these tissues, again, are built up the various organs of the 
body. All of this differentiation and segregation is carried on under the 
controlling influence of a central governing power which co-ordinates the 
parts for the welfare of the whole. 



Chapter II 
DEVELOPMENT OF MAN 

THE development of man is to be considered under two aspects : First : 
The development of species from an undifferentiated unicellular 
animal to the highly specialized creature now inhabiting the 
earth, is known as Phylogeny. Second: The development of the 
individual in one generation from the single cell to the adult form is called 
Ontogeny. 

Our knowledge of phylogeny is largely a matter of reasoning from the 
observed relations of animals to each other and from the order in which 
they have appeared on the globe. 

The two processes correspond so closely that it has become almost 
an axion of biology that the individual, in its development, recapitulates 
the stages and follows the order of the development of the species. In 
this chapter both divisions will be considered under one head. 

In the preceding chapter, it was shown that every living being begins 
life from a cell, or egg, by the union of two germ cells, one from the male 
and the other from the female. This fertilized cell, and its future develop- 
ment, forms a new being of the same species as the parent. Fig 10 illustrates 




Figure 10 

The germ cell or egg of vertebrates (modified from Animal Studies, Jordan, Kellogg and 

Heath). 1, fish; 2, reptile (frog); 3, bird; 4, mammal (human). 

the germ cell, or egg, of vertebrates, namely, a fish, reptile, bird and mammal, 
or human. 

15 



16 



DEVELOPMENTAL PATHOLOGY 



From the morula stage on, there are three important factors in develop- 
ment: first, the differentiation of cells which form the different animal 
tissues; second, their arrangement and grouping into organs or body parts; 




fl 



l\ li IV £% jf If' vk 



w 



: tj&. urn 



hi 



/ 

III. 



fish 



ixxm an cler- 



jb/to/'se Chick 



■M 



Rabbit 



Figure 11 
Different vertebrate animals in successive embryonic stages (Haeckel) . I, first or earliest of 
the stages figured; II, second of the stages; III, third or latest of the stages. 



A STUDY IN DEGENERATIVE EVOLUTION 



17 



and third, the development of these organs and body parts into the form 
characterizing the species to which the developing creature belongs. From 
the primitive indistinguishable cells of the blastoderm, development leads 
to certain cell type of muscular, bony and nerve tissue; from this generalized 
condition, the embryo, in its early developmental stages, passes to the 
special condition of the full grown animal. All many-celled animals are 
alike in the early, or first stages, of their formation, that is to say, each 
body is composed of a single cell. This similarity continues through several 
stages, when the embryos begin to differ and each assumes its own special 
type. This divergence of the embryos in the course of their development 
is aptly illustrated in Fig 11, which shows embryos from fish, reptile, 
bird and mammal. In the first stages of embryonic development no 
difference can be detected, in the second the divergence is more noticeable, 
while in the third there is nothing in common. 

Illustration of Phylogenetic Development. A good example 
of the way in which an animal in its individual development passes from 
the shape of an animal of a lower order to that of one of a higher order is 
seen in the development of an insect. The butterfly (Fig. 12), as is well 




Figure 12 
The transformation of the butterfly from the egg (the primitive cell), (modified from Animal 
Studies, Jordan, Kellogg and Heath). 1, the primitive cell; 2, the larva; 3, the pupa; 
4, the completely formed butterfly. 

known, lays an egg (1) which is a unicellular animal, a protozoan. This 
egg divides into two cells, these two into four, the four into eight, the 
eight into sixteen and so on (Fig. 6) and assumes the form of a multicellu- 
lar animal of very simple structure. The changes which take place in the 
cells represent different stages in the development of the animal which is 



18 



DEVELOPMENTAL PATHOLOGY 



to be produced. In this instance, it then develops into a being having 
the form and structure of a worm (2). This worm, known as a caterpillar, 
emerges from the egg and pursues, for a time, an existence similar to that 
of the worm. It then undergoes a transformation through the chrysalis 
(3) by which it becomes a member of a higher order or class of insects (4). 
Another still more instructive example of development, following the 
order of ascent from a lower to a higher class and from one order to another 
in the higher class, is that of the frog (Fig 13), which develops from an 
egg through the stages described for the caterpillar, but leaves the egg in 
the form of a fish. Like a fish (1), it breathes by gills, has a two-chambered 
heart and swims about in water by means of a tail. It has no developed 




Figure 13 
The evolution of the frog from the tadpole (modified from Animal Studies, Jordan, Kellogg 
and Heath). 1, tadpole with branching gills; 2, gills absorbed and hind legs have 
appeared; 3, four legs have appeared and absorption of the tail has begun; 4, complete 
absorption of the tail and fully developed frog appears. 

limbs. It feeds on vegetables. The vertebrae are biconcave as in fishes. 
Up to this point, the development of the fish and of the frog are very much 
alike, but the fish stops here and remains without limbs or lungs, breathing 
always by gills. In the frog, on the other hand, limbs begin to bud out 
and the lungs begin to develop and the external gills soon disappear, al- 
though the internal ones persist for a while longer. The creature can now 



A STUDY IN DEGENERATIVE EVOLUTION 19 

breathe both air and water. In this stage it resembles an amphibian of 
a low order, called the siren. Both the frog and the siren pass through the 
fish stage, but the siren stops at the next stage, retaining its tail and its 
gills, while the frog loses both. It develops a three chambered heart. 
Before it has completely lost its tail, it resembles an order of amphibia 
higher than the siren, to which the triton belongs. In the course of develop- 
ment, both the frog and the triton pass through the fish and siren stage 
into the triton stage, where the triton stops, while the frog goes on to the 
complete development of a higher order. The tail is now completely lost 
and the vertebrae assume the ball and socket type. At this period of 
transformation from a water to a land animal, hind legs (2) begin to develop 
through the skin. At a later date the fore-legs (3) develop. Fingers and 
toes, too, appear. Stretched between them is a web which allows the 
animal to swim with legs and feet, instead of a tail, as well as to hop about. 
While this process is occurring on the external surface, internal changes 
are taking place. The branching external gills are absorbed and lungs 
are developed from an enlargement and pouching of the walls of the esopha- 
gus. Blood vessels, too, develop throughout the structures. This change 
allows the animal to rise to the surface of the water and float with ease. 
The new development allows the animal to extract oxygen from both the 
air and water. He becomes a new being (4) with the change of environ- 
ment, some of the old structures remain useful and are retained, while 
others become useless and are discarded. Some of the old structures are 
modified to adapt themselves to the new environment. 

The teeth develop and the animal becomes insectivorous. The diet 
of the tadpole changes from a vegetable to animal food and the alimentary 
canal undergoes an entire change in harmony with the new environment. 
In this development of the frog, two important features are to be noted. 
First, the animal passes from a lower to a higher type, under the law of 
evolution, from the class of fishes to that of the amphibia. Second, this 
development is accomplished by the dwindling and disappearance of some 
organs and the new development of others. These changes, which take 
place in evolution, have been interpreted by different scientists in different 
ways. Thus : 

Aristotle called it the law of economy of growth, whereby an organ or 
structure is lost for the benefit of the organism as a whole; Lucretius showed 
long ago how the strongest survive and the weak are laid low, or survival of the 
fittest; Lemarck called it use and disuse of structures; while Darwin, harmon- 
izing these different views, called it natural selection; Roux called it the physio- 
logic struggle for existence between the organs, the cells and protoplasmic 
molecules of the organism, and Osborn, in the study of animals, termed it 
the law of compensation. 



20 



DEVELOPMENTAL PATHOLOGY 

Phytogeny 



Phylogeny is an Evolution of Man as a Race from a unicellular 
form, like the amoeba, through more and more complex forms that resemble 
those of the lower animals until it produces the characteristic human form. 
A strong evidence of the order of this development is seen in the intrauter- 




FlGURE 14 

The human embryo in its successive stages corresponding to Haeckel (original), 
stage; % the second stage; 3, the third, human stage. 



1, first 



A STUDY IN DEGENERATIVE EVOLUTION 21 

ine development of the embryo. The first cell produced by the union of 
the male and female genital cells (spermatozoon and ovum) multiplies by 
division until it forms a mass of cells resembling the morula (mulberry- 
like form), Fig. (>, No. 5. In this state, the embryo resembles a colony of 
undifferentiated protozoans. The mass then begins to assume shape and 
is seen to consist of layers of cells somewhat differentiated. So far, the 
changes are such as we might naturally expect in the formation of a large 
mass of cells destined to take the human form. The formation of the 
primordial central system, and the rudimentary spinal column, mark the 
transition to a vertebrate type, but no one could tell by mere observation 
whether the embryo was that of a fish, amphibian, sauropsidae (reptile 
and bird) or mammal; the type is the general one of the vertebrate but 
not the specific one of any of these divisions. 

But now a singular thing occurs. The embryo takes the form of a 
fish before it passes into that peculiar to the mammalian type. There 
appears a tail and, especially, gill slits, which indicates an animal fitted for 
breathing gases dissolved in water, Fig. 11, No. 1. Man then passes from 
the fish stage through the sauropsidian (reptile and bird) stage into the 
type characteristic of the mammal, Fig. 11, No. 2. One cannot say, 
however, from observation of the embryo at this stage whether it is that 
of the camel, dog, ape or man. It corresponds to the general type of the 
class, but not to any specific order. As the evolution proceeds, it takes 
more and more a specific character and terminates in the production of 
the fully formed human infant, Fig. 11, No. 3. 

The embryo of man, therefore, exhibits a similar passage through 
vertebrate forms resembling the fish, the reptile, the bird, the lower mam- 
mal, the lower monkeys, the higher apes, until the fully developed child 
resembles the lower forms of mankind, Fig. 14. 

Like the frog, man accomplishes his development by the disappearance 
of some features peculiar to the lower forms and by the addition of charac- 
teristics belonging to the higher forms. In the case of those structures 
which disappear, the disappearance is gradual and frequently is not com- 
plete, so that structures that were fully developed in the lower forms and 
served a useful purpose may be represented in man as degenerate or vesti- 
gal, that is, of no apparent use. 

"The theory of evolution, then" as Shute says, "teaches that this 
development of man in the course of a few short months, like the develop- 
ment of the frog, is a very condensed and abbreviated epitome of the 
evolution of mankind from primitive protozoans during the incalculable 
ages of the past. " 

The animal world of today may be conceived of as the twigs of a tree 
of which many have sprung from a common branch, and these common 



m 



DEVELOPMENTAL PATHOLOGY 



branches from an earlier one, etc. Just as the leaves, twigs, branches and 
trunk of a tree have a common origin, viz., the seed that developed into 
the tree, so all the different species of animals of the present and past are 
the trunk, branches, twigs and leaves of the "tree of life" and have had a 
common origin — from a primitive protozoan cell. (See diagram of develop- 
ment, Fig. 15.) 

iDAt) 



(CM 

S*OB ANTmROBOBiThE 

m:D ftORai A (Gor 
MOB SlMlA (Oi 
MOD HTL0BATE3 
MOD. CEBCOPIT 



MOD LtMuBO 




MOO AVE5 
MOD RtPT/LIA 



MCD GANOlDE. 



MOD MARSlpOBBAN 
MOD LEPTOCARDll 

MOD TUMCATA 



MOD 



oA(di«soci&ted) 



"•WMjflfaflraM (dissociated) 



Figure 15 
Diagram of development (Smite). Portion of the "Tree of Life" showing approximately 
the relative places of the great groups of animals. The central trunk and primary 
branches represent primitive (geologic forms); the terminal twigs represent modern 
forms. Man, like other animals, is a generalized development from the protozoa not 
from any special type of metazoa. In his development, therefore, he does not repeat 
all the steps of phylogeny but assumes the essential character of the race very quickly. 



A STUDY IN DEGENERATIVE EVOLUTION 23 

When life began as a primitive cell this cell contained potentially all 
the animal forms that have existed on the globe, just as the fertilized egg 
contains potentially all the tissues and organs of the adult man. 

The ancestors of man and of all the forms that belong to the present 
class of mammals, at one time belonged to the class of protozoans (simple 
cell), their successors were metazoa (higher than protozoa, having an 
ectoderm and endoderm). The successors of these were worms. Some 
of these worms developed into primitive fishes, and from these some develop- 
ed into modern fishes, while others became the primitive amphibia (lowest 
vertebrates which breathe air). From amphibia sprang reptiles, leaving 
behind some of their kind which remained amphibia and have produced 
the frogs and toads of today. 

From reptiles some passed on to become primitive mammals, (verte- 
brates whose females have milk-secreting organs). Of these primitive 
mammals, two preserve certain reptilian peculiarities. They are not 
warm blooded, like birds and mammals, but have a temperature far lower 
than these. Both these mammals (the duck-bill and spiny ant eater) 
lay eggs. In the spiny ant eater, the skin, at the time of egg laying, forms 
a pouch over the abdominal mammary gland. In this pouch, the eggs 
are deposited and hatch. This is a connecting link between the reptiles 
in whom the young are hatched just before exclusion and the pouched 
mammals (marsupialia). The primitive mammals were of different 
classes. Some remained almost stationary and their descendants are the 
marsupials of today, like the kangaroo. Others advanced to become the 
common ancestors of the monkey and man. These primitive primates 
had both pithecoid (simian-like) and anthropoid (man-like) characters. 
Some of these developed the tail to a marked extent and became tailed 
monkeys; others lost the tail and more and more became beings much like 
the modern chimpanzee. Some of these lived in trees and retained the 
use of the feet for grasping, like the gorilla and orang-outang of today. 
Others, leaving the trees and living on the ground, used the feet tor walk- 
ing the hands more for grasping, and became primitive man. They 
assumed the upright posture and their bodies became modified in related 
ways to suit their new mode of life. Particularly, the development of the 
brain began to dominate the course of evolution and the structure of the 
body was modified and subordinated, to a certain extent, to that of the 
dominant central nervous system. 

In tracing the descent of man, it must not be supposed that the ances- 
tors of man were altogether like the modern representatives of the primi- 
tive forms through which he has passed. The reptile-like ancestors of 
man were unlike the modern reptiles. They lacked in two respects the 
characters of modern reptiles. First, they were not specialized in the 



24 DEVELOPMENTAL PATHOLOGY 

manner of modern reptiles. This is well illustrated by Shute in the follow- 
ing passage: 

"To illustrate what has occurred at each stage in the evolution of 
man, pause for a moment to consider that phase of progress represented 
by the primitive reptilia. If we study the anatomy of the specialized 
reptiles, birds and monotremes (toothless mammals) of the present, we 
will find that they have many characters in common. These characters 
are reptilian. Each class has its own distinctive, specialized peculiarities 
in addition to its common reptilian characters. The study of the fossils 
of the rock shows that in the Jurassic and cretaceous ages, animals existed 
that were undoubtedly reptiles, but had also very distinct bird-like charac- 
ters; also reptiles existed that had distinct monotreme characters. These 
reptiles came from those of earliest times that were still more generalized. 
As the ages passed, some of the generalized reptiles (primitive reptiles) 
lost more and more their reptilian features, and gradually, assumed more 
and more distinct bird characters until, finally , the highly specialized modern 
birds ("glorified reptiles") were evolved, as a branch, from the primitive 
reptiles. So also with the modern reptiles and modern monotremes. 
They are specialized forms of these general primitive reptiles." 

It is not, therefore, correct to say that man is descended from the 
ape. The ape of today is a specialized descendant of the common ancestor, 
and man is another specialized form of this common being. 

The anthropoid ape, at the early period of life, often presents characters 
quite unlike those of the adult, Fig. 16. While the young anthropoid is 
comparatively human, the adult ape is comparatively bestial in character. 
The young ape has a smooth, globular, head and relatively small face, like 
man. The profile is more human w T ith little prognathism. The base of 
the skull is formed in a more human way than in the adult ape. The brain 
is relatively very much larger than in the adult. In the gorilla, for example, 
the fetus differs from the adult by having relatively a much larger head, 
a longer neck, a more slender trunk, shorter thumb and great toe; while 
the head is more globular, the face less prognathous and the hand more 
man -like. In nearly all these characters, the fetal gorilla approaches man. 
The adult male ape rapidly develops into a condition far removed from 
his early man-like state. The brain becomes relatively very small, the 
receding skull becomes hideous with huge, bony crests, sharp angles and, 
on its enormously enlarged facial portions, prominent outstanding super- 
ciliary ridges, projecting jaws and receding chin, while the dark, hairy 
body becomes more bestial in character. The female ape remains midway 
between the infantile and the adult male condition. So far as man is 
ape-like, it is infantile rather than the adult form which he resembles. 
Man, in the course of his life, falls away more and more from the specifically 



A STUDY IN DEGENERATIVE EVOLUTION 



25 



human type of his early years, but the ape, in the course of his short life, 
goes very much farther along the road of degradation and premature 
senility. The ape starts in life with a considerable human endowment, 
but in the course of life falls far away from it. Man starts in life with a 
still greater portion of human or ultra human endowment and to less 
extent falls from it in the adult life, approaching more and more to the 





Figure 16 
Comparison of the skulls of the young and adult gorilla with the human (British Museum 
Guide to Mammalia). A, the skull of an adult gorilla. The degeneration of the brain 
and skull for the benefit of the jaws and teeth is marked. B, skull of a young gorilla. 
It is at this period that resemblance to the human is most marked. C, the skull of an 
adult man. In his evolution from the lower vertebrates, the jaws and teeth have 
degenerated for the benefit of the brain. The opposite condition of A. 



ape. Up to birth, or shortly afterwards in the higher animals, such as the 
apes and man, there is a rapid and vigorous movement along the line 
upward in zoologic evolution. A time comes, however, when this fetal 
or infantile development, ceasing to be upward, is so directed as to answer 
to the life wants of the particular species. Henceforth and throughout 



26 DEVELOPMENTAL PATHOLOGY 

life there is chiefly a development of lower characters, a slow movement 
towards degeneration and senility, although one absolutely necessary to 
insure the preservation and stability of the individual and species. 

Fetal evolution, which takes place sheltered from the world, is in an 
abstractly upward direction. After birth, further development is a 
concrete adaptation to the environment without regard to upward zoologic 
movement. The infantile condition in both ape and man is somewhat 
alike and approximates to the human condition. The adult condition of 
both, also, tends to be somewhat alike and approximates to the ape-like 
condition. 

The human infant presents, in an exaggerated form, the chief distinctive 
characteristics of humanity, the large head and brain, the small face, the 
hairlessness, the delicate bony system. By some strange confusion of 
thought, this fact is usually ignored and it is assumed that the adult form 
is more highly developed than the infantile form. From the stand-point 
of adaptation to environment, the coarse, hairy, large-boned and small- 
brained gorilla is better fitted to make his way in the world than the delicate 
offspring, but from a zoologic point of view anything but progress occurs. 
In man, from about the third year onward, further growth, though an 
absolutely necessary adaptation to the environment, is, to some extent, 
growth in degeneration and senility. It is not carried to so low a degree 
as in the apes, although by it man is, to some extent, brought nearer to the 
apes. Among the higher human races, the progress toward senility is 
less marked than among the lower human races. The child of many African 
races is scarcely, if at all, less intelligent than the European child. The 
African, as he grows up, however, becomes stupid, obtuse, and his whole 
social life falls into a state of hide-bound routine. The European retains 
much of his child-like vivacity. The highest human types represented 
in typical men of genius are a striking approximation to the child type. 

Another character which differentiates the common ancestor from the 
multitudinous forms of the animal world as we see them today is the 
plasticity of his organism as compared with theirs. If men were swept 
from the earth today, there is little reason to suppose that a new human 
race would develop from the existing animal types. It must be assumed 
that these primitive ancestors possessed a capability of evolution not to 
be seen in the ordinary animal types of today. 

Summary 

The development of man is regarded from the view-point of phylogeny, 
or the development of the species, and ontogeny, or the development of 
the individual. 



A STUDY IN DEGENERATIVE EVOLUTION 27 

The individual, in his development, recapitulates the stages and 
follows the order of the development of the species. The ontogeny repeats 
in abbreviated form, the phylogeny. However, the net tendencies of 
phylogeny and ontogeny are opposed to each other, phylogeny tending to 
racial progress, ontogeny to individual adaptation. 

The embryo of man passes through forms representing protozoa, 
metazoa, primitive vertebrates, fish, reptiles, lower mammals, primitive 
apes and finally man, differentiating itself from each successive species 
as it develops upward. 

As evolution proceeds, useless structures disappear or become rudi- 
mentary, and new and useful structures are added. This principle is well 
illustrated in the evolution of the frog from the tadpole and the butterfly 
from the caterpillar. 

The primitive type from which man and other animals descended 
had more general characters and a more plastic organism than the forms 
descended from it. 

The fetal and infantile stages approach this common type and 
represent the racial or phylogenetic development of the species. As the 
adult stages supervene the phylogenetic influences are overshadowed by 
the ontogenetic, the organism becoming specialized to meet the life-require- 
ments of the individual, and losing its plasticity, so that further phylo- 
genetic development is stopped. 

Hence it is in fetal and child life that phylogeny is best studied; in 
adult forms, that ontogeny is best represented. Hence also those species 
in which fetal life and infancy are longest contribute, ceteris paribus, 
most to phylogenetic progress. 



Chapter III 
DEVELOPMENT OF ORGANS 

The Brain 

ONE characteristic of development is that each organ pursues the 
same type of development as the organism considered in the 
previous chapters. Each organ develops from a single cell. By 
mitosis, the cell divides and forms a community of cells, which become 
specialized into particular organs. The organ then undergoes the various 
changes according to environment from a lower to a higher order, as observed 
in the invertebrates and vertebrates already described. The intention is 
to discuss such phylogeny and ontogeny only as have particular bearing 
upon structures under later discussion. A good example is that of the 
brain. 

The brain, the central nervous organ, presides over development of 
tissues controlling nourishment to each one, whether a man or his organs 
shall develop normally or abnormally is thus determined. The phylogeny 
and ontogeny of it, therefore, interests the student at this time. 

The Phylogeny of the Brain 

The Brain of Fish. Fig. 17 represents the brain of an average bony 
fish. It consists of six swellings in a line, one before the other. Beginning 




Figure 17 
Brain of bony fish (modified from Hert- 
wig's Manual of Zoology, Kingsley). 
1, dorsal view; 2, side view; m, 
medulla; n, nerves; cl, cerebellum; ol, 
optic lobes; cb, cerebrum; of, olfactory 
lobes. 









1 




warn' i 


fr^fcw..^ 


T-^^P 


n 


B& i 1 

7s 


Jirt CB 


of 


At 


ci 




fc&i 



Figure 18 
Brain of frog (modified from Hertwig's 
Manual of Zoology, Kingsley). 1, 
dorsal view; 2, side view; m, medulla; 
cl, cerebellum; ol, optic lobes; cb, 
cerebrum; of, olfactory lobes; on, 
optic nerve. 



28 



A STUDY IN DEGENERATIVE EVOLUTION 



29 



from the end towards the spinal cord, they are designated as follows: a 
single median lobe, the medulla (metencephalon) , m; in front of this is 
another single median lobe, the cerebellum (epencephalon) , cl; then the 
optic lobes (mesencephalon), right and left, ol; then the thalami (thalamen- 
cephalon), which are small and hidden from view by the encroachment 
of the two adjacent segments; then the cerebrum (prosencephalon) cb; 
and, finally, the olfactory lobes (rhinencephalon) . In this fish the largest 
of the segments are the optic lobes, ol. 

The Brain of Reptile. The reptile's brain (Fig. 18), shows similar 
parts with the same serial arrangement. The reptile is a higher, more 
intelligent animal than the fish and, in consonance with this fact, the cere- 
brum, not the optic lobes, is the larger more dominant part of the brain. 

The Brain of the Bird is more closely related to that of the reptile 
than the brain of the reptile is to the frog brain. This last is in the same 
class as the fish (ichthyopsida) . The bird and reptilian brain is more 
closely related to the brain of the egg-laying mammals than to the brain 
of the higher mammals. The optic lobes, which were most prominent 
in the fish and less prominent in the reptile, are hardly visible in the bird 



jfasc N 


I 

\i 


s /v\^MK 


ON 


H ^oi Clr 






I 


v T»j> 





Figure 19 
Brain of bird (modified from Hertwig's Manual of Zoology, Kingsley). 1, dorsal view; 2, 
side view; m, medulla; cl, cerebellum; ol, optic lobes; cb, cerebrum; of, olfactory lobes; 
on, optic nerve. 

(Fig. 19), being almost covered by the cerebellum, showing a slight advance 
in evolution. 

In the Marsupial or Mammal (Fig. 20), a more intelligent animal 
still, the cerebrum (cb) , has grown so large that it extends backwards and 
partially covers the optic lobes. In the marsupial, the cerebellum (cl), 
(like the cerebrum, cb), has evolved to a higher phase. It consists of a 
median lobe (cb) , which is larger than the median cerebellum of the lower 



30 



DEVELOPMENTAL PATHOLOGY 



animals described and of two lateral lobes, one on either side, which have 
been acquired in the course of evolution. The median lobe, the homologue 
of the single median cerebellum of lower animals, is larger than the lateral 
ones. The cerebellum of the marsupial has its surface increased by fissures, 
while that of the fish, reptile and bird is smooth. The fissured cerebellum 




Figure 20 
Brain of lemur (modified from Shute). 1, dorsal view, 2, side view; m, medulla; cl, cerebel- 
lum; cb, cerebrum; of, olfactory lobes. 

is a higher evolution than the smooth ones. In the groups of animals 
referred to so far the cerebrum is smooth and the olfactory lobes are still 
in front, though much encroached upon in the marsupial by the enlarging 
cerebrum. In those animals still higher in the scale, like the prosimia 
(lemurs), the cerebrum has reached yet greater proportions and complexity 
and has grown still farther backwards towards the medulla, so that it 
hides from view a considerable portion of the cerebellum (Fig. 20) ; it has 
also grown forward, concealing largely the olfactory lobes. The cerebrum, 
no longer smooth, has a number of simple fissures and convolutions (the 
higher animals have numerous complex fissures and convolutions). The 
lateral lobes of the cerebellum have increased relatively more than the 
central lobe, and the whole organ has advanced in complexity of fissures. 
In the higher simiae (monkeys and apes) the cerebrum has grown so far 
backwards as to cover almost completely the cerebellum and medulla and its 
convolutions have become more numerous and complex. . The cerebellum 



A STUDY IN DEGENERATIVE EVOLUTION 



31 



has also grown greatly and its lateral lobes are now larger and more complex 
than the central lobe. 

Finally in Man (Fig. 21), the whole brain has grown so enormously 
that it is three times larger than the brain of the highest simiae. The 
cerebrum, especially, has increased enormously in size. It has grown 
not only backward (overlapping cerebellum), upward and downward on 





"%; /'■■' 



Figure 21 
Brain of man (Carus's "Soul of Man"). Dorsal and side views. The cerebrum has grown 
so far backwards and forwards as completely to hide the other segments of the brain 
when looked at from the dorsal surface. 



the sides, it has grown so far forward as not only to cover the olfactory 
lobes, but also to project far beyond them. The cerebellum has also 
increased in size and complexity, especially the lateral lobes. The ideal 
vertical section (Fig. 22), shows diagrammatically in one figure all these 
stages in the evolution of the human brain through the geologic ages. 



32 



DEVELOPMENTAL PATHOLOGY 



The Ontogeny of the Brain 



Very early in the development of the fetus, at about the second week, 
there occurs complete closure of the anterior end of the neural tube. The 
cephalic region of this tube is slightly flattened from side to side and 
presents an appearance of an unequal growth. Two slight constrictions 
occur, dividing the medullary tube into three enlargements, known as 
primary brain vesicles. 

In the development of the human brain from the fertilized ovum, 
the stages which are permanent in the zoologic (taxonomic) series, are 
transient stages. 

Early Development of the Human Brain presents three swellings 
in a serial arrangement. They are known from behind, forwards as the 




Figure 22 
Diagrammatic sketch of the phylogeny and ontogeny of the brain (modified from LeCount) . m , 
medulla; cbf, cerebellum of fish; olf, optic lobe of fish; erf, cerebrum of fish; of, olfactory 
lobes of fish; cbr, cerebellum of reptile; ebb, cerebellum of bird; cbo, cerebellum of opos- 
sum; cbl, cerebellum of lemur; cbm, cerebellum of man; mm, medulla of man. The 
convolutions of the cerebrum in phylogenic development begin with the lemur; in the 
cerebellum from the oppossum. 

hind-brain, mid-brain and fore-brain. The fetal brain, in developing 
from this early condition to a later and higher state, differentiates the 
hind-brain into the medulla (Fig. 23, m), and the cerebellum, (cl); the 
mid-brain becomes the optic lobes, (ol); and the fore-brain differentiates 
into the thalmi (th) and the cerebrum (cr). A little later the cerebrum 
buds forth the olfactory lobes (of) so that the human brain will consist 
of six fundamental segments, — one behind the other. This is the fish 
stage in the growth of the human brain (compare Fig. 23, (1) with Fig. 17). 



A STUDY IN DEGENERATIVE EVOLUTION 



33 



As development proceeds, the most conspicuous growth of the brain 
occurs in connection with the cerebrum and cerebellum (Fig. 23,2). The 
cerebrum grows relatively and actually larger and larger, but does not 
yet cover any portion of the optic lobes. This is the reptile stage, (Fig. 18). 
The cerebrum, continuing to grow (Fig. 23, 3), finally covers the front 
portion of the optic lobes. This is the marsupial stage (Fig. 20). Growing 
further, it soon covers a greater or less portion of the cerebellum. These 
are the prosimian- (lemur) and simian stages. Finally it grows so far 
backward as to completely cover the cerebellum and so far forward as to 
project much beyond the olfactory lobes. This is the human stage (Fig. 
23, No. 4). 




Figure 23 
Brain of human embryo in its ontogenic development (His). 1, the fish stage; 2, the reptilian 
stage; 3, the bird stage; 4, the mammal or human stage; m, medulla; cl, cerebellum; ol, 
optic lobes; th, thalmus; cr, cerebrum; of, olfactory lobes. 



The Cerebrum in fish, reptile, bird and lower marsupial (mammal) 
is smooth. In the half apes (lemuroidae) it is convoluted; in the simidae, 
it is still more convoluted, while in man it reaches the climax of complexity 
in the size, number, and sinuosity of its convolutions. These convolutions 



34 



DEVELOPMENTAL PATHOLOGY 



increase the surface of the cortex of the brain, which is the seat of psychic 
phenomena. Other things being equal, the greater the amount of cortex, 
the greater is the intelligence. During its embryonic development, the 
human cerebrum passes through the stage of smoothness to a convoluted 
condition; then through stages of increasing complexity of convolutions. 
Simultaneously with this advance of cerebral organization, occurs an 
unfolding of increasing intelligence. 

The Cerebellum presides over the co-ordination of the muscular 
movements of the body. It, also like the cerebrum, passes through the 
fish, reptile, bird, marsupial, lemur and simian phases. At first, it consists 
only of the median lobe; then the lateral lobes appear, at first small in 
size, but getting larger and larger until they greatly surpass in bulk the 
more primitive median portion. At first, the cerebellum is smooth, but 
ARC D 



^ ^F~ 




e d c b a 

Figure 24 
Shows the evolution in phylogeny and ontogeny of the pyramidal cells of the brain (Ramon 
y Cajal). The upper series of cells represents the psychic cell in various vertebrates; 
A, the frog; B, the lizard; C, the rat; D, man. The lower series show the progressive 
stages in the evolution of the pyramidal cell in the human brain; a, the neuroblast without 
protoplasmic processes; b, the appearance of the nerve process and of the terminal 
ramifications; c, the nerve more fully developed; d, appearance of lateral branches of 
the axis cylinder; e, development of protoplasmic outgrowths of the protoplasm of 
nerve cell and nerve. 



as it develops, its fissures become greater and greater, thus increasing its 
cortex. With the developing cerebellum are associated increasing powers 
of muscular co-ordination; increasing delicacy and complexity of muscular 
movements. 

Between birth and three months, the brain is one-fifth the weight of 
the body. In the adult it is one thirty-third. During the first six months, 
the brain doubles in weight. The effects of stress at this time would, 
under the law of economy of growth, be felt either in diminution of the 



A STUDY IN DEGENERATIVE EVOLUTION 35 

quality or quantity of the brain or in the preservation of these at the 
expense of more transitory structures like the face, nose, jaws and teeth. 
In other words, when a given amount of nutriment is sent to the head, 
there is a struggle between the face, jaws, teeth and brain for the material. 
If the jaws succeed in obtaining the most there is a return to the anthropoid, 
the brain becomes proportionately smaller and the jaws larger. On the 
other hand, if the brain receives the most nutriment, it develops at the 
expense of the face and jaws. Between two years and six, the same factors, 
to a lesser degree, are present, while between seven and fourteen, the brain 
has quadrupled in weight. 

The Neuron Cell Unit of the cortex of the brain, passes successively 
through stages corresponding to those which are to be found in the adult, 
fish, reptile, bird and mammal (Fig. 24). Here the development consists 
in an increasing complexity of the cell with no formation of unnecessary 
rudimentary parts. This is also the case when the development of the 
brain of man is compared with the probable ancestral stages as displayed 
in the vertebrate series. Arrest of development of the neurons would 
imply imperfect power of association and consequently imperfect potent- 
ialities of education. The brain of man passes, by a long course, through 
a phase of development in which mental powers, unknown in the ape or 
merely rudimentary, become highly developed; and as the organ of the 
mind, the brain remains capable of expansion almost, or quite, to the end 
of normal life. The nervous and muscular systems retain a power of 
development by which the execution of new movements can be learned 
until late in life. Fixity is reached, for the most part, only in those organs, 
like the skeleton, for which there is no need of adaptation with advancing 
development. Thus the ontogeny of the brain and its neuron recapitulates 
its phylogeny. 

In his flight from cell to fully developed compound animal, man, at 
the present period of his evolution has, as a result of a loss in explosive 
force, developed a nervous system. How well he accomplishes this develop- 
ment depends upon brain health. The nervous system of man develops 
first, to preside over the development of the other structures. If it be 
normal, the structures of the body will develop normally; on the other 
hand, if from any cause it be abnormally developed, unstable or defective, 
the structures of the body, while developing, become abnormal. When 
arrests of the brain occur, different classes of degenerates result. The 
more marked forms are the idiot, insane, criminal, periodical drunkard, 
deaf-mute and congenital blind. The one-sided genius, the habitual liar, 
the "smart" business man, the extreme egotist, the tramp, kleptomaniac, 
harlot and pauper likewise belong here. All display stigmata (deformities, 
signs) to a marked degree. 



36 DEVELOPMENTAL PATHOLOGY 

All organs of the body have practically an individual nervous system, 
which exercises a control over their nutrition through its control over the 
blood supply and the means of excretion. The excessive action of this 
local nervous system is restrained by the central system for the benefit 
of the organism as a whole (inhibition). Should the central nervous 
system become improperly developed, relaxed in check action or weakened, 
the local nervous system, given free play, first draws nourishment and 
increased power at the expense of other organs. As a result of this increased 
power, the local nervous system becomes itself exhausted and a struggle 
for existence occurs between its parts. In consequence, as in the case of 
tumors and cancers, cells take on the power of local reproduction which, 
for a long time, they had lost, for the benefit of the organism as a whole. 

Summary 

Organs develop from single specialized cells and, with the rise in the 
animal scale, usually show advance from a lower to a higher state by 
increasing complexity of organization. The brain controls the development 
of other organs. 

In phylogeny, the changes in the brain are characterized by the 
increase in size and in complexity of two parts, the cerebellum and the 
cerebrum, which, in the fish, are smaller than the optic lobes, but in man, 
overshadow and cover all the other parts of the brain. The increase in 
size and complexity of the cerebrum is closely associated with increase in 
intelligence. In the fish, both cerebellum and cerebrum are smooth; in 
man they are fissured and complexly convoluted. 

In ontogeny, the human brain begins by an infolding of the epiblast, 
which forms, at the anterior end, three swellings, the hind-brain, the mid- 
brain and the fore-brain. These form, later, the medulla, the cerebellum, 
the optic lobes, the thalami and the cerebrum from which spring the 
olfactory lobes. The cerebrum, at first small and smooth, grows so as to 
cover the cerebellum and extends far beyond the olfactory lobes, and its 
surface is divided and corrugated into numerous folds and convolutions. 
The surface is called the cortex; with the increase in amount of cortex, 
there is a corresponding increase in the amount of intelligence. 

The cerebellum co-ordinates muscular movements, and, in proportion 
to the complexity of its development, the power of performing delicate 
and finely co-ordinated movements increases. 

The individual neurons of the brain undergo a development correspond- 
ing to the forms observed in the lower animals. 

A struggle for existence between the brain and the jaws and teeth may 



A STUDY IN DEGENERATIVE EVOLUTION 37 

result in imperfect development of the brain or in a similar imperfection 
on the side of the jaws and teeth. 

The development and functionation of the various organs is under 
the control of local nervous systems and all of these are in turn controlled 
bjr the brain, which co-ordinates and restrains them for the good of the 
whole. 

Imperfect development of the brain and disturbance in its controlling 
force, therefore, account for many deformities and abnormal traits of body 
and mind. 



Chapter IV 
DEVELOPMENT OF ORGANS 

The Heart and Great Arteries 
Phylogeny 

STUDY of blood vessel phylogeny must begin with the annelids (Class 
Vermes or Worms). Above and below their digestive tract is a 
longitudinal blood vessel connected in each section by loops passing 
around the intestine. In them, the place of the heart is taken, functionally, 
by contractile blood vessels. This is also the casein the lancelet (amphiox- 
us), the lowest vertebrate. Below its pharynx, in the endostylar coelom, 
is a more or less contractile blood vessel (the branchial artery) , which 
corresponds in its position and relations to the heart and aorta of the 
higher forms. The higher vertebrate types develop a heart in the ventral 
trunk (dorsal of the annelids). 

In Fish, the heart close behind the gills, sends them blood from the 
body, which, like that of the whole ventral, is venous. The dorsal trunk 
collects from the gills oxygenated blood, which is sent by the carotids to 
the head, and by the dorsal aorta and vascular loops to the body, where 
it becomes venous, flowing again into the ventral trunk. The heart, a 
strong muscular organ in a pericardium, consists of two parts, auricle and 
ventricle, separated by valves. The trunk (ventral aorta) arising from 
the auricle is arterial and corresponds to the ascending aorta and pulmon- 
ary artery of man. The arterial branches of the gill region, which arise 
from it, pass directly into the dorsal vessel only in young fishes ; later they 
furnish the branchial circulation of gill arteries, gill capillaries, and gill 
veins. The dorsal trunk is the dorsal aorta (aorta descendens) ; the ventral 
trunk (present in the embryo only), is the sub-intestinal vein, from which 
the portal vein arises. To this are added a system of paired veins, consist- 
ing of Cuvierian ducts, jugular and cardinal veins, the latter gradually 
encroach on the territory of the sub -intestinal vein. 

Fish type circulation undergoes a great modification with the loss of 
gills and the appearance of pulmonary respiration. Gills and gill capillaries 
disappear. Branchial circulation is reduced to arterial arches leading 
direct from the ventral to the dorsal aorta. The swim bladder received 
its blood from the body (systemic) circulation, but with the functioning 
of the lungs, pulmonary arteries and veins come into existence, while the 

38 



A STUDY IN DEGENERATIVE EVOLUTION 



39 



arterial arches in part disappear and in part are divided between the 
pulmonary and systemic circulations (Fig. 25). Of the six arches which 
usually appear in the embryo, the first and second and, in animals with 
lungs, the fifth usually disappear. The last arch (4), which even in the 
Dipnoi supplies the swim bladder, becomes a pulmonary artery; the other 
arches (1 and 2) furnish the systemic portions, the dorsal aorta (2) and the 
carotids supplying the head (1). 



// 



111 



IV 




Figure 25 
Diagram of modification of arterial arches in the various vertebrate classes (Kingsley, Hert- 
wig's Manual of Zoology). White vessels which degenerate; cross-lined, vessels con- 
taining arterial blood; black vessels containing venous blood. I, Dipnoi (sub-class of 
fish); II, Urodeles (an order of amphibians) with pulmonary respiration; III, Reptiles; 
IV, Birds, (in mammals the left instead of the right aortic arch persists) . ao , venous 
aorta of reptiles; ao", arterial aorta; ast, arterial trunk; a, b, arches which usually dis- 
appear; ad, dorsal aorta; d, B, ductus Botalli; k, gill capillaries; pu, pulmonary artery; 
1-4, persistent arterial arches. 

Since the special pulmonary veins, distinct from the systemic circula- 
tion, carry the blood from the lungs to the heart, the heart becomes divided 
by a septum which separates it into right and left halves. The right half 
retains the venous character of the fish heart; since the right auricle receives 
the systemic veins, the right ventricle gives off the pulmonary artery. 
The left half is purely arterial, receiving arterial blood by the left auricle 
from the lungs and sending it out through the aorta ascendens to the body. 
A complete separation of pulmonary and systemic circulation, and a 
corresponding division of the heart, occurs only in birds and mammals. 
Amphibia and reptilia show how the modification has been accomplished. 
In these, separation begins in the venous system and extends to the auricle; 
in reptiles, the septum arises in the ventricle. In the arterial system, 
remnants may persist, such as a connection (ductus Botalli) of the pulmo- 
nalis with the aorta (II, d b) , or an aortic arch may rise with the pulmonalis 
from the right side of the heart (III, ao). 

In the Gilled Batrachia, the type intermediate between tadpole 



40 DEVELOPMENTAL PATHOLOGY 

and adult, gilled batrachian persists during life. Blood propelling force 
in reptiles consists of a heart with two auricles and one ventricle. Oxy- 
genated blood from the lungs is forced into the left auricle. The impure 
blood passes into the right auricle. As the animal has but a single ventricle, 
the two blood streams mix to some extent, as they pass into the general 
circulation. In some salamanders, the lungs often disappear and breathing- 
is carried on by the skin. 

In Reptiles, the circulation greatly improves over that of the amphi- 
bia. The partition of the ventricle is not complete, however, and the pure 
blood becomes mixed with the impure in its return to the heart. In some 
reptiles, as the alligators and crocodiles, the partition is complete and the 
circulation resembles that of the mammal. 

In Birds, blood circulation assumes a higher type than in reptiles. 
Complete separation of the systemic and pulmonary systems takes place. 
Of the three great arterial trunks connected with the circulation in the 
crocodile, the pulmonary artery and the right aortic arch arising from the 
left ventricle are retained; the left venous arch is lost. The septum (in 
heart evolution) between the ventricles is complete in the bird. The bird 
ranks higher than the egg-laying mammals. Certain mammals, like the 
dugong (sea-cow), have a heart which, while united, presents a double 
appearance. The ventricles are separated. The heart type of the vivipa- 
rous (live-born) mammal is essentially that of the bird. 

The bird being warm blooded, the heart has arrived at its highest 
development in its evolutionary stage from the pulsating branchial artery 
of the lancelet through the two-chambered organ of fishes, and the three- 
chambered organ of reptiles to the four-chambered organ of the higher 
viviparous mammals. 

Ontogeny of the Great Vessels 

Ontogeny of the blood vessels closely follows phylogeny. Correspond- 
ing to the four visceral arches are four vascular arches. One of these 
disappears, and the remaining three undergo certain changes, by which 
they are converted into the vessels going to the head and the superior 
extremities. The anterior arches on the two sides are converted into the 
carotids and subclavians; the second, on the left side, is converted into 
the permanent aorta and the right is obliterated; the third, on either side, 
is converted into the right and left pulmonary arteries. 

The branchial arch changes are illustrated in Fig. 26. In this the 
three branchial arches that remain and participate in the development 
of the upper portion of the vascular system are 1, 2, 3, on either side. The 
two anterior (3, 3) become the carotids (c, c) and the subclavians (s, s). 



A STUDY IN DEGENERATIVE EVOLUTION 41 

The second (2, 2) is obliterated on the right side and becomes the arch of 
the aorta on the left side. The third (1,1), counting from above downward, 
is converted into the pulmonary arteries of the two sides. Upon the left 
side, there is a large anastomosing vessel (ca), between the pulmonary 
artery of that side and the arch of the aorta, which is the ductus arteriosus. 
The anastomosing vessel (cd), between the right pulmonary artery and 
the aorta, is obliterated. 




Figure 26 
Transformation of the system of aortic arches into permanent trunks in the mammalia 
(Von Baer). B, aortic bulb; 1, % 3, 4, 5, on either side, the five pairs of aortic arches; 
5, 5, the earliest in their appearance; 1,1, the most recent; c, c, the two carotids, still 
united, which are separated at a later period; s, s, the two subslavians, the right arising 
from the arteria in nominata; a, a, the aorta; p,p, the pulmonary arteries; ca, the ductus 
arteriosus; cd, the left arterial canal, which is finally obliterated. 

Vein Development is very simple. Two venous trunks make their 
appearance by the sides of the spinal column, which are called the cardinal 
veins, and run parallel with the superior vertebral arteries, or the two 
aortae, empting finally into the auricular portion of the heart, by two 
canals, which are called the canals of Cuvier. These veins change their 
relations and connections as the first circulation is replaced by the second. 
The omphalo-mesenteric vein opens into the heart between the two 
canals of Cuvier. As development advances, the liver is formed in the 
course of this vessel, a short distance below the heart, and the vein ramifies 
in its substance; so that the blood of the omphalo-mesenteric vein passes 
through the liver before it goes to the heart. The omphalo-mesenteric 
vein is obliterated as the umbilical vein makes its appearance. The blood 
from the umbilical vein is at first emptied directly into the heart; but this 
vessel soon establishes the same relations with the liver as the omphalo- 



42 DEVELOPMENTAL PATHOLOGY 

mesenteric vein and its blood passes through the liver before it reaches the 
central organ of the circulation. As the omphalo-mesenteric vein atrophies, 
the mesenteric vein, bringing the blood from the intestinal canal, is 
developed, and this penetrates the liver, becoming finally the portal vein. 

As the lower extremities are developed, the inferior vena cava makes 
its appearance, between the two inferior cardinal veins. This vessel 
receives an anastomosing branch from the umbilical vein before it penetrates 
the liver and this branch is the ductus venosus. As the inferior vena cava 
increases in size, it communicates below with the two inferior cardinal 
veins; and that portion of the two inferior cardinal veins which remains 
constitutes the two iliac veins. The inferior cardinal veins, between that 
portion which forms the iliac veins and the heart, finally become the right 
and left azygos veins. 

The right canal of Cuvier, as the upper extremities are developed, 
enlarges and becomes the vena cava descendens, receiving, finally, all the 
blood from the head and the superior extremities. The left canal of Cuvier 
undergoes atrophy and disappears. The upper portion of the superior 
cardinal veins is developed into the jugulars and subclavians on the two 
sides. As the lower portion of the left cardinal vein and the left canal of 
Cuvier atrophy, a venous trunk appears, connecting the left subclavian 
with the right canal of Cuvier. This increases in size and becomes the 
left vena innominata, which connects the left subclavian and internal 
jugular with the vena cava descendens. 

Ontogeny of the Heart 

The first traces in the development of the human heart occurs about 
the tenth or twelfth day, in the form of a mass of cells proceeding from 
the middle layer of the blastodermic vesicle and the anterior wall of the 
intestinal cavity. It soon forms a bent tube lying in front of the embryo 
and only connected to it by its vessels. The heart is situated at first at 
the anterior end of the embryo, lying opposite the last two cerebral vesicles. 
As the head is developed, the heart falls, as it were, backwards to the lower 
part of the neck and then to the thorax. It fills the whole thoracic cavity 
about the second month. As the lungs and thoracic parietes form, the 
heart assumes its permanent position. 

This hollow cellular structure elongates into the tube, which very 
soon assumes a shape somewhat like an S (Fig. 27) and there are indications 
of its being subdivided into (a) an upper aortic part with the bulbus 
arteriosus; (b) a middle or ventricular part; and (v) a lower venous or 
articular part. The heart then curves on itself in the form of a horseshoe 
(2) so that the venous end (A) comes to lie above and slightly behind the 



A STUDY IN DEGENERATIVE EVOLUTION 



43 



arterial end. On the right and left sides respectively, of the venous part 
is a blind hollow outgrowth which forms the large auricle on each side 
(3, o, o). The flexure of the body of the heart corresponding to the great 
curvature (2, V) is divided into two large compartments (3), the division 
being indicated by a slight depression on the surface. The large truncus 
venosus (4, v), which joins with the middle of the posterior wall of the 
auricular part, is composed of the superior and inferior venae cavae. This 
common trunk is absorbed at a later period into the enlarging auricle and 
thus arise the separate terminations of the superior and inferior venae 
cavae. In man, the heart soon comes to lie in a special cavity, which in 
part is bounded by a portion of the diaphragm (His.). 




Figure 27 
Development of the heart (Landois and Stirling). 1, early appearance of the heart, a, 
aortic part with the bulbus, b; v, venous end. 2, horseshoe shaped curving of the heart 
— a, aortic end with the bulbus, b; V, ventricle; A, auricular part. 3, formation of the 
auricular appendages, o, o 1 , and the external furrow in the ventricle. 4, commencing 
division of the aorta, p, into two tubes, a. 5, view from behind of the opened auricle, 
v, v, into the L, and R, ventricles, and between the two latter the projecting ventricular 
septum, while the aorta (a) and pulmonary artery (p) open into their respective ventri- 
cles. 6, relation of the orifices of the superior (Cs) and inferior vena cava (Ci) to the 
auricle (schematic view from above) — x, direction of the blood of the superior vena cava 
into the right auricle; y, that of the inferior cava to the inferior cava to the left auricle; 
tL, tubercle of Lower. 7, heart of the ripe fetus- — R, right, L, left ventricle; a, aorta 
with the innominate, cc, carotid, c, and left subclavian artery, s; B, ductus arteriosus; p, 
pulmonary artery with the small branches 1 and 2 to the lungs. 

The Chambers. At the fourth to fifth week, the heart begins to be 
divided into a right and a left half. Corresponding to the position of the 
vertical ventricular furrow, a septum grows upward vertically in the 
interior of the heart and divides the ventricular part into a right and left 



44 DEVELOPMENTAL PATHOLOGY 

ventricle (5, R. L.). There is a constriction in the heart, between the 
auricular and ventricular portions, forming the canalis auricularis. It 
contains a communication between the auricle and both ventricles, lying 
between an anterior and posterior projecting lip of endothelium, from which 
the auriculo-ventricular valves are formed (F. Schmidt). The ventricular 
septum grows upward toward the canalis auricularis and is complete at 
the eighth week. Thus, the large, undivided auricle communicates by a 
right and left auriculo-ventricular opening with the corresponding ventricle 
(5). At the same time two septa (4, p a) appear in the interior of the 
truncus arteriosus (4, p), which ultimately meet, and thus divide this 
tube into two tubes (5, a p), the latter forming the aorta and pulmonary 
artery, and are disposed toward each other like the tubes in a double- 
barreled gun. The septum grows downward until it meets the ventricular 
septum (5), so that the right ventricle comes to be connected with the 
pulmonary artery and the left with the aorta. The division of the truncus 
arteriosus, however, takes place only in the first part of its course. The 
division does not take place above, so that the pulmonary artery and aorta 
unite in one common trunk above. This communication between the 
pulmonary artery and the aorta is the ductus arteriosus Botalli (7, B). 

Vascular Relations. In the auricle, a septum grows from the 
front and behind, ending internally with a concave margin. The vena 
cava superior (6, Cs) terminates to the right of this fold, so that its blood 
will tend to go toward the right ventricle, in the direction of the arrow in 
6, x. The cava inferior, on the other hand (6, Ci), opens directly opposite 
the fold. On the left of its orifice the valve of the foramen ovale is formed 
by a fold growing toward the auricular fold, so that the blood current from 
the inferior vena cava goes only to the left, in the direction of the arrow, y; 
on the right of the orifice of the cava and opposite the fold, is the Eustach- 
ian valve, which, in conjunction with the tubercle of Lower (tL), directs 
the stream from the inferior vena cava to the left into the left auricle 
through the pervious foramen ovale. After birth, the valve of the foramen 
ovale closes that aperture, while the ductus arteriosus also becomes imper- 
vious, so that the blood of the pulmonary artery is forced to go through 
the pulmonary branches proceeding to the expanding lungs. Sometimes 
the foramen ovale remains pervious. 

Though the heart is composed at first of a mass of fetal cells, its 
rhythmic contractions can be observed even in this condition before the 
development of any muscular fibres, and even, according to some authors, 
before it is in connection with any nerve fibres. 

At birth, the heart is small relatively to the arterial system, but this 
disproportion gradually disappears until puberty when, according to 
Beneke, the relation is changed. The larger the heart, relatively, to the 



A STUDY IN DEGENERATIVE EVOLUTION 45 

vessels, the higher the blood pressure and the earlier, stronger and more 
complete is the development of puberty. The weight of the heart from 
birth increases twelve and a half times. Strain, interfering with heart 
growth would either affect it or, under the law of economy of growth, the 
more transitory structures are lost for its benefit. 

Arrests in Phylogeny and Ontogeny of heart development appear 
in cardiac malformations such as the partitions of the heart remain unde- 
veloped at the ichthyopsida (certain fishes) and reptilian stage. These 
frequently occur in so-called "blue babies." 

In mammals, the aorta normally passes to the left of the vertebral 
column; in reptiles it divides and passes to both sides. Not infrequently 
in ontogeny there is an arrest in phylogeny in which the arch divides and 
passes to both sides at the reptilian stage. Hommel, in 1737, was the first 
to record findings of this character. Meckel noticed an abnormality in 
which the two divisions united after encircling the trachea. 

In transplantation of the viscera, as occasionally found in the dissect- 
ing room, appearance of the aorta and the heart are found upon the right 
side is a reversion to the bird type. 

Heart malformations, as based on analysis of four hundred and twelve 
specimens, show arrests and excessive development existing at birth. 
Many of these, studied from a phylogenetic standpoint, show persistence 
in the adult stages of fish, reptile, bird, oviparous and lower mammal 
tendencies. 

Summary 

Phylogeny 

In the lowest types of animal life, the annelids and amphioxi, the heart 
is simply a more or less contractile blood vessel, corresponding in position 
and relations to the heart and aorta of the higher animals. 

In fish, the heart is a strong muscular organ in a pericardium, with 
auricle and ventricle, separated by valves, receiving oxygenated blood 
from the gills by the dorsal trunk, and venous blood from the body of the 
ventral. This type of circulation is radically modified with the disap- 
pearance of gills and the establishment of pulmonary respiration. Special 
pulmonary arteries and veins now appear, and with this separation of the 
pulmonary from the systemic circulation, the heart is divided by a septum 
into right and left halves. The complete separation is only achieved in 
birds and mammals, but in the amphibia and reptilia, the intervening 
modification is seen. 

In reptiles, the circulatory system shows a great advance over that 



46 DEVELOPMENTAL PATHOLOGY 

of the amphibia. The septum arises in the ventricle, but the partition is 
incomplete, so that the arterial and venous blood become mixed in their 
return to the heart, and in the arterial system remnants of the old order 
of things frequently persist, such as connections between the pulmonary 
artery and the aorta, etc. In some of the higher reptiles, the partition is 
complete, and the circulation similar to that of mammals. 

In birds, the circulation shows a much higher development than in rep- 
tiles, and, in fact, higher than in the egg-laying mammals, being essentially 
the same as in the viviparous mammal. The heart is a four-chambered 
organ which is fundamentally the highest stage of its evolution ; separation 
of the pulmonary and systemic circulations is complete; and the arterial 
and venous economy is essentially the same as in the higher mammals. 

Ontogeny 

The ontogeny of the vessels is a replica of their phylogeny. The 
heart first assumes a hollow, elongated, tubular shape, which subsequently 
bends on itself, the flexure being divided into two large compartments. 
At the fourth to the fifth week in the human fetus the heart begins to be 
divided into right and left halves, a septum growing up through the ventri- 
cle, followed later by the downward growth of a septum dividing the 
auricle, which meets the ventricular septum. The arteries and veins 
follow a corresponding structural and relational development. 

Rythmic contractions are observable in the heart even in its elementary 
cellular condition, and, according to some authorities, before its connection 
with nerve fibres. 

At birth, the heart is relatively small compared with the arterial 
system, the disproportion gradually disappearing until at puberty, when 
the relativity is reversed. This constitutes one of the points of strain in 
puberty. The greater the relative size of the heart in the child, the better 
the development at puberty. 

Arrests in heart development are sometimes seen of both a phylogenetic 
and an ontogenetic character, which manifest themselves as malformations 
(perforated septa, divided aortae, etc.). 



Chapter V 
DEVELOPMENT OF ORGANS 

The Liver 
Phylogeny 

THE Phylogeny of the Liver begins in a co-operative way in different 
developing structures known as hepato-pancreas or liver pancreas. 
Later on each part becomes a complete separate organ with its 
special function. 

The Amphioxus has a blind pouch, lined with columnar epithelium 
secreting a digestive fluid, and known as the liver or hepatic caecum. 

The Dog Fish has a large liver composed of two elongated lobes, with 
a gall bladder at the anterior end of the left lobe. Ducts connect the gall 
bladder with the right and left lobes of the liver; a duct opens into the 
beginning of the colon. 

In the Trout, the liver is imperfectly developed into two lobes. The 
gall bladder is comparatively large. 

In the Frog, the liver is early recognizable as a diverticulum pushed 
out from the front end of the digestive tract in a ventroposterior direction. 
The walls of this diverticulum thicken and become folded, and the meso- 
blast penetrates between these folds. The liver is two-lobed. The 
diverticulum (evidently lined with entoblast) persist as the bile duct. 
From it, an outgrowth arises to form the gall bladder which lies between 
the two lobes. 

Lizards have a two-lobed organ. The ontogenetic advance seems 
to be marked by the change of position of the gall bladder, which lies at 
the lower margin of the right lobe. 

In the Chick, the origin of the liver as a median outgrowth from 
the floor of the digestive tract, occurs as in the frog. 

"The liver arises (Marshall) about the middle of the third day, as a 
tubular diverticulum from the posterior end of the fore-gut, in the angle 
between the two vitellin veins, and immediately behind their point of 
union. A second diverticulum arises from the same spot, almost directly 
afterwards; it is similar to the first, but of rather smaller size. Both these 
diverticula have hypoblastic walls, with thin, mesoblastic investments. 

"Towards the latter part of the third day, as the folding off of the 
embryo from the yolk-sac proceeds, the liver diverticula are found to arise 

47 



48 DEVELOPMENTAL PATHOLOGY 

definitely from the part of the mesenteron, which will later become the 
duodenum. At the same time, they come into very close relation with 
a very large median vein, the meatus venosus, which is formed by the 
union of the right and left vitellin veins behind the heart. 

"The two liver diverticula lie on each side of the meatus venosus, 
and in very close contact with this. The hypoblastic cells, forming the 
walls of the diverticula now begin to proliferate freely, growing out as 
solid strands of cells, which form an irregular reticulum, closely surround- 
ing the meatus venosus ; the meshes of the reticulum being occupied by the 
capillary blood vessels, which develop in the mesoblast, and early acquire 
connection with the meatus venosus itself. These processes proceed 
rapidly during the fourth and fifth days, and by the end of the fifth day, 
the liver is a solid organ of considerable size, consisting of a network of 
solid rods of hypoblast cells, which branch and anastomose freely in all 
directions; the meshes of the network being occupied by blood vessels 
which penetrate all parts of the liver and are in free communication with 
the meatus venosus round which the liver is formed. 

"The liver continues to grow rapidly. By the tenth day, it is the 
largest organ in the abdomen. The trabecular network of hypoblast 
cells becomes the liver parenchyma; the tubular diverticula, from the 
duodenum, branch out freely in the substance of the liver and become the 
two bile ducts of the adult bird; while the gall bladder arises on the fifth 
day as a sacular outgrowth from the right, or larger, of the two primary 
diverticula. " 

The early formation of the liver in the chick, and its large size during 
the greater part of the developmental history, indicate its functional 
importance during embryonic life. Its relation to the blood system, and 
especially the fact that it intercepts the blood returning from the yolk-sac 
to the heart, indicates that its chief purpose is elaboration of food material 
from the yolk-sac by which nutrition of the embryo is affected. 

Mammalian Development. Marked developmental changes are 
seen in the liver of the rabbit, which is five-lobed. A fold of peritoneum 
attaches it to the diaphragm. Hepatic ducts from the gall bladder unite 
to form a common bile duct, which opens into the duodenum. 

In other mammals, the liver consists of two parts of main divisions, 
right and left, incompletely separated from one another by a fissure termed 
umbilical, owing to its marking the position of the fetal umbilical vein. 
Usually, each of these main divisions is divided by a fissure into two parts, 
so that the right lateral and right central and left lateral and left central 
are distinguishable. When a gall bladder is present, as it is in the majority 
of mammals, it is attached to or imbedded in the right central lobe. A 
fissure, the portal, through which the portal vein and hepatic artery enter 



A STUDY IN DEGENERATIVE EVOLUTION 49 

the substance of the liver, and hepatic vein passes out, crosses the right 
central lobe near the anterior border. The post-cavel lies in contact with, 
or imbedded in the right lateral lobe near its anterior border, and given 
off from this lobe between the post-cavel and the portal fissure, is a small 
lobe of varying extent — the spigelian. The term caudate lobe is applied 
to the process of the right lateral lobes of considerable extent in most 
mammals, having the post-cavel vein in intimate relation to it and often 
closely applied to the kidney. A gall bladder is usually present. It is 
absent in the Cetacea, Hyracoides, in some rodents, the Perisodactyl and 
Ungulata. 

Ontogeny 

The development of the human liver is similar to that of the chick 
and mammals. The liver has undergone similar changes to the kidney, 
being an older organ in phylogeny of vertebrates than the heart. Embryo- 
logically and morphologically, it is composed of two distinct parts, one 
related to excretion and the other to secretion, assimilation, glycogenesis, 
sanguif action and metabolism. These parts are first a branching system 
of epithelial gall ducts, and secondly a network of hepatic cylinders. 

The Gall Ducts are surrounded by connective tissue, and, as is 
well known, are accompanied by the branches of the portal vein and 
hepatic artery. 

The Hepatic Cylinders are separated from one another only by 
endothelial blood vessels. The essential primitive features of the hepatic 
cylinders are an epithelial tube with a small central lumen and covered by 
an endothelium, which is easily recognized by its flattened, darkly-stained 
nuclei; the endothelium is the wall of a blood vessel or channel. The 
hepatic cylinders, by branching and uniting, form a network, all the meshes 
of which are entirely occupied by blood vessels. In sharks, each cylinder 
comprises in its cross section, usually, eight or ten cells and is almost com- 
pletely bathed in blood. In amphibia, the cylinders are smaller; they 
comprise only four to five cells in cross section, their lumen is very small, 
and the blood channels between them are relatively diminished. In 
mammals, each hepatic cylinder comprises merely two epithelial cells; 
the lumen is reduced to a minute canal (the gall capillary) ; the cylinders 
anastomose with one another very frequently and at very short intervals; 
and, finally, the blood vessels between the cylinders become smaller, for 
the most part, than the cylinders. In mammals, the hepatic cylinders 
are gathered into radiating groups; the groups are the lobules of descriptive 
anatomy. 

Fetal Development. The liver commences, as stated, as a diverti- 



50 DEVELOPMENTAL PATHOLOGY 

culum of the endodermal canal, extending into the septum trans versum. 
This single median diverticulum may be designated as the amphioxus 
stage, since a similar diverticulum in the cyclostome is regarded, probably 
correctly, as the homologue of the primitive hepatic anlage of true verte- 
brates. From this point, the liver passes through the different stages of 
typical development from fish to reptile and from bird to mammal. 

During the second month of fetal life, the liver is relatively enormous; 
during the third month it fills the greater part of the abdominal cavity. 
After the fifth month, the intestines and other viscera overtake the liver; 
still the liver of the child at birth is twice the size of that of the adult. 
Immediately after birth, the liver diminishes. The right lobe, always 
larger than the left, increases in predominance after birth. Very early in 
fetal life, the liver becomes the principal seat of blood formation. As 
Claude Bernard has shown, the glycogenic function of the liver begins in 
the embryo. After birth, the nutritive function of the liver becomes 
subservient to the excretory function. This is shown by the atrophy of 
the hepatic cylinders described by Toldt and Zuckerkandl. Arrest of 
development at certain times would produce the diabetic states, so fatal 
to children. Such arrest, resembling phylogenetic development, may result 
from premature senility, from strain arising before but evinced during the 
first dentition, or from effects of constitutional disorders at early periods 
of stress. While the liver does not entirely lose its originally great poio- 
genetic powers, still these proportionately decrease with the evolution of 
the rest of the poiogenetic agencies in the embryo. 

Summary 

Phytogeny 

The liver has its beginnings, in combination with the pancreas, as a 
double or co-operative structure, which later separates into two distinct 
organs. 

Its early formation in the various species is indicative of its functional 
importance to fetal life as an elaborator of nutrition. 

Structurally, its evolution is marked by division into lobes and later 
into two parts, right and left, incompletely separated from each other by 
a fissure. Functionally, by its less and less activity as a nutrient organ 
and its more and more importance as an excretory one. 

Ontogeny 

Here, as elsewhere, ontogeny is a replica of phylogeny. It is developed 
by a co-operation between the hypoblastic cells, forming the epithelium 



A STUDY IN DEGENERATIVE EVOLUTION 51 

of the digestive tract, and the mesoblastic cells which form the connective 
tissue framework. The mucous membrane forms a pouch which divides 
and ramifies until it forms the complicated system of biliary canals. 
The connective tissue carrying the blood vessels and the parenchymatous 
liver cells, is grouped in lobules around the terminal biliary ducts. 

The liver is developed in two portions, right and left. Its relative 
importance is greatest in fetal life. Its originally great blood-forming 
functions decrease in importance as other blood making organs are devel- 
oped. Its detoxicating powers increase. 



Chapter VI 
DEVELOPMENT OF ORGANS 

The Kidney 
Phylogeny 

THE earliest phase of kidney is the contractile vacuole of the protozoa. 
Increased specialization of cells is brought about in two ways; a 
greater number of cells involved in the changes and increased 
functional activity meet the growing demands. The progress is regular. 
The water vessels of the planaris, the nephridial tubes and anal opening 
of the Nemertinae, the excretory vein and pore of the ascaria, all evince 
advance. 

In the Lowest Vertebrate, (the amphioxus), the excretory function 
is carried on by ninety pairs of peculiarly modified nephridia, situated 
above the pharynx and in relation with the main coelomic cavity. 

In Craniata, the dog fish furnish type of early kidney development. 
In the dog fish "each kidney consists of two parts, anterior and posterior. " 
The former is a long, narrow ribbon of soft, reddish substance which runs 
along throughout a great part of the body cavity at the side of the vertebral 
column. The ducts of the anterior portion are narrow tubes which dilate 
and form a pair of elongated chambers, the urinary sinuses, which unite 
into a median sinus, opening into the cloaca. The ureters are developed 
in the dog fish, being the ducts of the posterior portion of the kidney. 
There may be four or six of these and they open into the urinary sinus. 

The Kidneys of the Trout differ somewhat from those of the dog 
fish. The progressive phase here is development of a urinary bladder. 
The ureters (mesonephric ducts) unite in a single tube which dilates to 
form the bladder. The kidneys are relatively large and are partly fused 
together in the median line. This condition re-appears in the "horseshoe" 
kidney of man. In adult life, the anterior portion is lymphatic tissue and 
the renal function ceases. 

In Amphibia, the adrenal body is developed. In the tadpole, a large 
pronephros is, for a time, the functionating kidney. From the mesonephros 
and mesonephric ducts of the embryo are developed the kidneys and 
ureters. There are a number of irregularly scattered nephrostomes ; 
these, however, do not connect with the urinary tubules, but serve to 
carry lymph from the coelom to the venous system. 

In Reptiles (the lizard), the kidneys show little or no distinctive 
change. Previous changes are more clearly and definitely outlined. 

52 



A STUDY IN DEGENERATIVE EVOLUTION 53 

In the Pigeon, the kidneys are developed from the metanephros, 
the mesonephros (or Wolffian body), undergoing complete atrophy. The 
more characteristic shape of the organ is about the only change noted. 

In Mammals, there is a firm, compact, oval organ. Vessels leave 
and enter at the hilus or notch. The central secreting portion, the medulla, 
is usually distinctly separated from the cortex, or outer portion which 
contains the straight tubules, carrying the secretion to the ureters. 

In some mammals (some primates, the carnivora and rodentia), this 
marked division of the kidney substance is absent, but in others (the 
bear, seal and cetacea) the markings are so accentuated that they extend 
to the external surface, dividing the organ into lobules. 

In the kidney of the rabbit, several phylogenetic changes are manifest. 
The shape is oval. The hilus is developed. In the ontogenetic develop- 
ment the relative position of the two organs shows an advance toward the 
kidney of man, — the right being slightly in advance of the left. The 
substance of the kidney shows the division into cortical and medullary 
areas. The pelvis of the kidney is noted for the first time, forming the 
dilated beginning of the ureters. 

In the development of the vertebrates, occurs an evolution of organs 
for disposing of urinary waste which, after serving the purpose of the lower 
members of the class, become unsuited to the conditions necessitated by 
advance in evolution and give place to a second set of organs better adapted 
to the complex needs of the more advanced species. The organs first 
developed appear temporarily in the higher animals, but, having given 
place to their more perfect successors, they atrophy or are devoted to 
other uses. 

Ontogeny 

Gain and Loss Process. In intrauterine development (ontogeny) 
the disappearing and developing tendency is peculiarly well illustrated 
in the embryogeny of the genito-urinary system, which in all vertebrates 
contains rudimentary organs. 

The Pronephros. The first stage in the formation of the kidney 
system is the pronephros (Fig. 28 a), which consists of intricate canals, 
(a, a, a,) opening into the body cavity at the point where the glomeruli are 
formed on the sub-intestinal vein. As a temporary structure, the prone- 
phros attains considerable development in many fishes and amphibians; 
in the higher animals, even as an embryonal, it remains very rudimentary 
and transient. These canals originally had apertures to the exterior. 
Later on, they became connected with one excretory canal (c) opening 
into the cloaca, [ce, sauropsidia (reptiles and birds)]. The primitive 
genital gland was situated close to the pronephros. 



54 



DEVELOPMENTAL PATHOLOGY 



The Mesonephros. In the process of embryogeny, the mesonephros, 
at first distinct from its origin, replaces the pronephros (Fig. 28, b). The 
mesonephros, a secretory urinary gland (g), with its secretory canal (c), 
(segmental duct), in appearance closely resembles the pronephros. The 
urinary system thus formed continues to be closely connected with the 
genital gland, the discharging canal of which passes through the mesone- 





FlGURE 28 

Development of the uro-genital system in higher vertebrates (DeMoor). A, pronephric 
stage; a, tubules; c, excreting duct; ce, cloaca; B, mesonephric stage; G, mesonephros; 
r, remains of pronephros; c, excreting canal; w, neutral genital gland; M, Muller's duct; 
ce, cloaca; C, metanephric or adult stage in the male; R, permanent kidney; U, ureter; 
V, bladder; T, testis, e and r, epididymis and vas deferens; s, vas deferens; hm, hydatid 
of Morgagni; h, hydatid; p, paradidymis; urn, uterus masculinus; D, metanephric or 
adult stage in the female; R, permanent kidney; U, ureter; V, bladder; 0, ovary; p and 
p 1 , parovarium and paraophron; w, Weber's organ; V, vagina; u, uterus; t, aperture of 
Fallopian tube; h, hydatid. 

phric kidney to find exit through the segmental duct. During the mesone- 
phric stage Muller's duct (m) forms, starting from the cloaca and opening 
out into the general body cavity. The mesonephros does not become 
the permanent kidney. 

The Metanephros. In the course of embryogeny, the metanephros 
(the permanent excretory kidney) develops Fig. 28 (cb). This develop- 
ment is attended by important modification; further instances of degenera- 
tion occur and fresh organic connections are established. In the male, 



A STUDY IN DEGENERATIVE EVOLUTION 55 

Fig. 28 (c), the mesonephros begins to atrophy. The part connected 
with the testes is transformed into the epididymis and the vas deferens 
(e and v). The remaining part atrophies. When the permanent organi- 
zation is attained, the atrophied part persists as a paradidymis (p), and 
a hydatid (h) — organs without functions in the adult state. The dis- 
charging canal, which during the mesonephric stage is common to both 
urinary and genital glands remains simply in connection with the testes 
and then becomes the vas deferens (s), the terminal extremity of which 
(the cloaca, having disappeared) becomes gradually individualized. The 
permanent kidney (r) is connected with a fresh canal — the ureter (u), 
formed by degrees at the expense of the primitive discharging canal and 
subsequently separated from the latter in order to empty itself into the 
bladder (v). Muller's duct, which first increases in size, proceeds at a 
certain stage to atrophy until all that remains are the distal and proximal 
extremities in reduced organs (the hydatid of Morgagni (h m) and the 
male uterus (u m), neither of which is functional. The intervening part 
of the duct remains to form the canal of Gasser. The adult male genito- 
urinary apparatus, therefore, comprises: (1) organs which have come 
into existence at different times, but which have retained their original 
functions — the testes, the kidneys (metanephros) and the ureter; (2) organs 
which are functional, but of which the ultimate function differs from the 
original — the epidiymis and vas deferens; (3) reduced organs, vestiges of 
what were formerly active organs — the hydatid and the paradidymis; 
(4) reduced organs, vestiges of Muller's duct which becomes active only in 
the female — the hydatid of Morgagni and the male uterus. 

Kidney Development in the Female (Fig. 28, b), is similar as to 
physiologic atrophy and hypertrophy. In that part of the mesenephros 
connected with the genital gland and the corresponding discharging canal, 
the canal, as a rule, disappears. Exceptionally it forms Gartner's duct 
(g). The lower part persists in a rudiment (Weber's organ (w) ); the 
upper part becomes reduced to a small tissue which surrounds the parova- 
rium (p), paraophoron (p) — vestiges of the former mesonephros. Muller's 
duct becomes considerably enlarged, forming the vagina, the uterus and 
the Fallopian tubes. At the upper end it is connected with the hydatid, 
a vestige of the mesonephros. The genito-urinary female apparatus 
contains some organs, the function of which remains unchanged — the 
ovaries, the permanent kidney, the Fallopian tubes, the uterus, the vagina, 
and the ureter; and some rudimentary organs (vestiges of once active 
organs) — the paraovarium, the paraophoron, hydatid and Weber's organ. 

The complicated development of this system becomes clear if careful 
study be made of the phylogeny of the genito-urinary apparatus. The 
various phases through which the embryos of the higher vertebrates pass 



56 DEVELOPMENTAL PATHOLOGY 

are stages similar to those which may be observed in the adult lower 
vertebrates. The principle of recapitulation, that the embryonic struc- 
tures of higher animals pass through the successive stages attained by the 
adults of lower animals, receives a full corroboration from the fact cited. 
The amphioxus, for instance, remains still at the pronephric stage; fish, 
at the mesonephric stage, or permanent kidney. Some lizards (lacerta) 
up to the age of two years make use of the mesonephros as the eliminating 
urinating organ. At the same time, they make use of the metanephros 
which is also functional. In chamoeles, the mesonephros remains partly 
active throughout life. Birds and mammals completely lose the mesone- 
phros and, in the adult stage, the metanephros is the only active kidney. 
Arrests in ontogeny, therefore, may take place at any of the adult stages 
of the lower vertebrates. In another chapter arrests in development of 
these structures will be considered. 

Congenital Abnormalities of the Kidneys may affect (a) their 
shape, size, and number; (b) their position; and the kidneys that are abnor- 
mal in one of these respects are apt to be so in others. 

(a) Abnormalities as to shape, size and number. — One kidney may be 
congenital^ absent or greatly atrophied; may be constricted so as to 
assume an hour-glass shape; or lobulated, as in the fetal condition; or the 
two kidneys may be fused so that (1) their inferior portions are united by 
a band of tissue — glandular or fibrous — that crosses the vertebral column, 
usually in the lumbar region ("Horseshoe kidney"). 

This condition is characterized by the presence of, at least, two ureters. 
There must, of course, be a marked change in the form and position of the 
kidneys, for even though one kidney occupy its normal position and the 
other one is joined to it, there must be an absence of kidney on the other 
side. The commonest form of double kidney is the horseshoe kidney 
(ren arcuatus). The "arch 1 ' is almost always made by the union of the 
lower ends of the two kidneys in front of the vertebral column. This 
gives the double organ a crescentic shape with its concavity upward. The 
reverse position is sometimes seen. The renal pelves are directed forward 
and both ureters and blood vessels are frequently increased in number. 
The attachment of the two kidneys may be slight, or it may be so complete 
that only a fold shows where the two are joined. One kidney may be 
over-developed and the other one small. This anomaly is found once in 
1100 autopsies, and once in about two hundred of the defective classes. 

A unilateral long kidney (ren elongatus), is much more rare. Both 
kidneys are then found on one side of the vertebral column and the lower 
pole of the upper kidney is united to the upper pole of the lower one by a 
thinner or thicker mass of parenchymatous tissue. The pelves of the 
kidney may be turned in opposite directions, giving an S shape to the 



A STUDY IN DEGENERATIVE EVOLUTION 57 

whole organ. In this condition, the ureter of the misplaced kidney crossed 
the abdominal vessels, the vertebral column and the ureter of the other 
kidney. 

The two kidneys may be united in a third form which has been com- 
pared to a shield (ren scutaneus). This form is the result of an intimate 
fusion of both kidneys to a round, more or less flattened organ, which 
usually lies in the center of the abdomen, rarely upon either side. 
There are generally two ureters. This type of abnormality may be looked 
upon as a horseshoe kidney, with union of both lobes and the posterior 
margins. The pelves form a groove in the center of the anterior surface, 
from either side of which springs a ureter. The vena cava crosses a portion 
of the kidney, while the aorta lies wholly behind it. 

An abnormality which possesses a far greater importance is the imper- 
fect development of one kidney (hypoplasia renis), or its entire absence. 
A hypoblastic kidney may be of any size. It may be made up of fibrous 
tissue, with some rudimentary tubules and glomeruli, or it may contain a 
certain amount of well-formed parenchyma. There may be cysts in the 
connective tissue. 

The ureter may be completely absent, or it may exist without a lumen, 
or it may be formed, but abnormally small. It may be obliterated in 
places and pervious in places. The pelvis of the kidney may be absent 
or rudimentary. It is worth mention that the lower portion of the ureter 
may naturally open into the bladder, so that the passage of the ureteral 
catheter for a certain distance is no proof of the existence of an active 
kidney. 

Defect of one kidney is frequently associated with defects or anomalies 
of the sexual organs and with other degeneracies. If one kidney be want- 
ing, the suprarenal capsule may be absent, but is usually present. The 
single kidney, usually normal in position and shape, may be malformed or 
misplaced. 

Congenitally absent kidney has been observed once in 3370 autopsies. 
Only a single kidney is four times as frequently absent among the defective 
classes. 

Both kidneys have been absent in many still-born children and acepha- 
lous monsters. In a very few cases, a supernumerary kidney has been 
found. 

Anomalies affecting the blood supply to the kidney occur in nearly 
fifty per cent of cases. The renal arteries are usually increased in number 
or divide at once — before reaching the bilum — into several branches, fetal 
conditions in the human species that are permanent in many birds and 
reptiles. Accessory or supernumerary veins are much more rarely found. 

Anomalies of position. — Congenital displacement — apart from the 



58 DEVELOPMENTAL PATHOLOGY 

horseshoe kidney — usually affects one kidney, which is apt to be found 
in the vicinity of the sacral promontory or the sacro-iliac joint, but may 
be either higher or lower, and maybe its malposition gives rise to serious 
or even fatal error in diagnosis or treatment. 

Summary 

Phylogeny 

In the lower vertebrates, the urinary excretory gland is developed 
from a pronephros, which is not the homologue of the kidney of the higher 
classes. The urinary bladder is not developed in the lower genera. In 
the tadpole, the pronephros is, for a time, the functionating kidney. The 
kidney of the adult frog is developed from the mesonephros. In the 
amphibia, the adrenal body is first developed. In the pigeon, the kidney 
is developed from another structure, the metanephros. In mammals, the 
organs become more compact and approach the form and position which 
it has in man. 

Ontogeny 

In man, the pronephros and mesonephros appear as transient structures, 
to disappear, giving place to the metanephros, which forms the permanent 
kidney. 



Chapter VII 
DEVELOPMENT OF ORGANS 

The Head and Face 
Phylogeny 

THE phylogeny of the head and face is, perhaps, the most interesting 
of all structures of the body. All organisms consist of developed 
cells and groups of cells. In compound organisms, the cells retain 
the potentialities of single-celled organisms, which, however, they surrender 
for the benefit of the whole organism. These potentialities are lighted 
into activity by disease or disorder of the co-ordinating mechanisms 
constituting the checks on local action for the benefit of the cell-commune 
or body. Cells, having resumed low embryonic types for the benefit of 
the body, retain the potentialities of the higher enbryonic, and circum- 
stances may stimulate these, either for the benefit of the body or of the 
cell itself. This appears in skull and face embryogeny. 

The Skull is a development, in part, of the vertebrae and, in part, of 
dermal or membraneous bones which, as in bony fish and reptiles, formed 
the protective armor of the skin of the head. As the head end of the spinal 
cord of the lancelet (amphioxus) grew (Fig. 29) in size the cartilage enclos- 




FlGURE 29 

Amphioxus lanceolatus from the left side, about twice natural size (Lankester) . The gonadic 
pouches are seen by transparency through the body- wall; the antrium is expanded so 
that its floor projects below the metapleural fold; the fin-chambers of the ventral fin 
are indicated between atriopore and anus. The dark spot at the base of the fifty- 
second myotome represents the anus. 



ing it developed to protect it. This was the earliest appearance of the 
skull in biologic (phylogeny), as in fetal (ontogeny) evolution. Later, 
another skull developed in connection with this. The skull, therefore, 

59 



60 



DEVELOPMENTAL PATHOLOGY 



has, as Minot remarks, a double origin; or rather, there are two skulls 
which were originally distinct. In evolution from the lowest fish to the 
highest mammal, and in human embryonic development, these become 
united. 

The Primary Skull is an extension of the vertebrae which send 
side-outgrowths to cover the brain, as the backbone covers the spinal 
cord. This primary skull (Fig. 30,) extended in front of thenotochord 




Figure 30 
Rabbit embryo of 6 mm (Mihalkovics) . Median longitudinal section of the head. The 
connection between the mouth, M, and the pharynx, ent, is just established; nch, noto- 
chord; hb, hind-brain; mb, mid-brain;/6, fore-brain; 'pro. am., proamnion; hy, hypophysis 
cerebri; ht, heart. 

(the spinal cord of the human embryo and the permanent spinal cord of 
the lancelet (amphioxus) or pre vertebrate (ascidian). In the lancelet, 
it gave off two trabeculae cranii, or front skull plates. In man, the primary 
skull (or chondrocranium) gives off (Fig. 31) two occipital or rear skull 
plates, and two plates midway between the trabeculae and occipals. 




Figure 31 
Chondrocranium of an insectivorous mammal (Tatusia). (W. K. Parker). 

"In describing this figure in detail," says Minot, "there is 
one remark to be made, namely, that here we have clearly shown the true 



A STUDY IN DEGENERATIVE EVOLUTION 61 

diagnostic mark of a mammalian skull. This mark is the rupture of the 
side walls, due to the pressure of the large lateral masses of the cerebrum. 
In front of the auditory capsules, there is a large semi-circular opening, 
the crown of the arch looking upward and forward. Only the lower half 
of the wall has thus broken outward; this 'fault' forms the alisphenoid, 
while the orbitosphenoid (o s), the so-called 'lesser wing,' is many times 
its size and is continuous over the archways with the cartilage that runs 
on backward into the supra-occipital region (s o). There is nothing 
similar to this in that sauropsidian skull which comes nearest to that of 
the mammal — the skull of the crocodile, while in birds the orbitosphenoids 
are very small, even when they are most developed, as in struthio, and in 
that class the alisphenoids almost finish the cranial cavity, being turned 
inward toward each other, on each side of the back part of the orbital 
septum. I lay special stress upon this rupture outward of the alisphenoid, 
and on the fact that the nasal roofs utilize the whole of the huge high- 
crested intertrabecula, because these are the most distinctive marks of 
the mammalian skull, and they arise from two things in which the mammal 
shows its great superiority to even the highest sauropsida, namely, the 
huge volume of the cerebrum and the tenfold complexity of the nasal 
labyrinth. A third clear diagnostic sign is seen in this very figure — this 
is the peculiar development of the antero-inferior part of the oblique 
auditory capsule, due to the development of the coils of the cochlea. So 
that, at once, correlated with the sudden expansion, so to speak, of the 
cerebrum, we have these new and most important improvements in the 
organs of smell and hearing. At first sight, seeing how large the median 
bar (intertrabecula) is, with its internasal crest (perpendicular ethmoid 
and septum nasi — p. e., s. n.), it might be supposed that the mammalian 
skull was of the high kind, like that seen in many teleostean fishes, lizards 
and in birds. It is not so, however, but belongs to the low kind, seen in 
selachians and amphibians, and, like theirs, is hinged on the spine by a 
pair of occipital condyles. Hence, the eye-balls are kept far apart, instead 
of coming very near each other, as in most birds, where often nothing but 
a membraneous fenestra is found between the right and left capsules and 
their special muscular apparatus. But the face, as well as the skull of the 
mammal, shows marks of excellence such as are not seen in the sauropsida, 
even in the higher kinds, as crocodiles and birds. The great development 
of the nasal organs is correlated with a most remarkable growth of the 
bones of the upper jaw and the palate to form the 'hard palate.' This is 
found in rudiment even in the chelonia and in birds, but especially in the 
crocodilia, where, however, its excessive development — as in certain 
edentates, (e. g.) myrmecophaga — is not dependent upon or correlated 
with any great improvement in the organs of smell, but has to do with 



fr2 



DEVELOPMENTAL PATHOLOGY 



the peculiar manner in which these monsters take their prey." These 
gradually inclose the primitive hearing apparatus, the otocysts (permanent 
in fish and embryonic in man), and are called periotic capsules. 

This primary skull is at first cartilaginous (Fig. 32) as in sharks. In 




Figure 32 
The cartilaginous skull of a shark. (Sutton). 

the fish, there is a progressive reduction of cartilaginous skull by which its 
covering over the brain is more and more demonstrated. This reduction 
leaves an opening on the dorsal side which calls for the space to be filled 
with dermal bones — frontals, parietals and interparietals. In reptiles and 
birds, the opening is larger than in fish, and in mammals still larger than 
in reptiles and birds. Reduction of the cartilages of the branchial skeleton 
also progresses from the lower to the higher vertebrates. 

It is clear from the above description that the evolution of the mammal- 
ian skull has depended to a large extent upon the degeneration of the inner 
skull for its shape and covering, showing the loss or degeneracy of some 
structures in evolution for the benefit of the organism as a whole. With 




Figure 33 
Skull showing fontanelles (Gray). 



A STUDY IX DEGENERATIVE EVOLUTION 



63 



the increase in the size of the brain in phylogeny and in ontogeny, this 
cartilaginous primary skull becomes insufficient to roof over the brain 
and gaps result. The fontanelles (Fig. 33) or soft places at the top, sides 
and back of the head of the new-born are expressions of this failure of the 
primary skull to cover the gains of the nervous system. This deficiency, 
while resultant on certain advances in evolution, would be a serious block 
to further advance or to life itself were it not that the fetal skin of mammals 
retains an osteogenic function, normal in reptiles, certain edentates and 
bony fish. This is an instance of the stimulation of cell potentiality for 
the benefit of the organism as a whole. 

Secondary Skull. These cavities were filled by dermal bones 
(Fig. 34) which, at first merely armor of the skin of the head, later became 




Figure 34 
Lateral view of skull of man forty-five years of age showing wormian bones (Charles A. 
Parker). This skull is a splendid illustration of the exaggeration of the evolutionary 
principles or law where certain structures are lost aud others gained for the benefit of 
the organism as a whole. The brain and skull have developed enormously while the 
bones of the face have lost in proportion. The lime salts intended for the bones of the 
face and jaws were required to cover the enormously developed brain. The material 
not being sufficient, one hundred and seventy-two wormian bones were required to fill 
the deficiencies. They were located at the posterior and lateral regions. 



64 



DEVELOPMENTAL PATHOLOGY 



protectors of the nervous system (the brain) . The following are representa- 
tive dermal bones in the embryonic human skulling. 

The frontals, which form the chief part of the forehead. The sutures 
or dovetails of these normally disappear in the adult, so that the forehead 
seems to be but one bone. This union may not occur (Fig. 35) as in the 




Figure 35 
Front view of skull showing open suture in center of frontal bones (Charles A. Parker). An 
imaginary line drawn through the center of the skull, nose and jaws shows marked 
irregularities in development. 

case of the philosopher Kant, who had a frontal suture all his life. The 
dovetails are replaced by solid bone through a process called synostosis. 
In the case of the frontal bone, synostosis is normal and in the line of 
advance. Elsewhere in the skull it expresses defect, giving rise to various 
cranial states, either absolutely degenerate in type or degenerate in certain 
races only. 

The parietals and interparietals, which are united by synostosis to 
form the parietals or side bones of the adult human skull. 



A STUDY IN DEGENERATIVE EVOLUTION 65 

The nasal bones, which, together with the vomer form the nose. 

The pterygoids and palatines. 

The maxillaries and premaxillaries which, with the mandibles form 
the jaws. 

The mandibles are in part derived from the chondrocranium. 

In the course of evolution, and during the progress of human embryonic 
development, these bones become fewer by the process of early cartilaginous 
union or synostosis. The openings in the skull resulting from the deficien- 
cies in the chondrocranium are larger in the sauropsida (birds and reptiles) 
than in the ichthyopsida (amphibians and fish); in the monotremata 
(egg-laying mammals) than in the sauropsida; in the marsupials (pouched 
mammals) than in the monotremata; and in the higher mammals than in 
the marsupials. Brain development, therefore, depends on the expanding 
power of the secondary skull formed by the dermal bones. These are 
degenerate bones, a mere reminiscence of that outer skeleton whereby 
early fish and reptiles emulated the lobster, whose outer covering has 
developed into a solid mass. Any check to development causing organism- 
degeneracy, is exerted on bone development itself, and finally, on the 
relation to other bones, or dove tailing. 

In accordance with the laws of economy of growth, deficiency in one 
place usually results in increase elsewhere. The brain-protective function 
of the dermal bones, being later in order of development than their old 
armor function, is checked by degeneracy in two ways — either the bone 
does not grow sufficiently in size to unite with its fellows, or this growth 
occurs for the benefit of the bone alone, and, therefore, union with other 
bones occurs too early to benefit the organism as a whole. To the factors 
underlying this latter condition is due the failure of increase in intellect 
after puberty in the higher apes and the lower human races. These 
checks likewise tend to nutritional advantage of the older primary skull, 
whence result irregularities in development that constitutes so many 
skull stigmata. The sutures sometimes fail to form because sufficient 
cartilage is not produced to fill the gaps (Fig. 33). These secondary gaps 
are often filled by new dermal bones called Wormian (named after Claus 
Worm). Sometimes this deficiency co-exists with too early synostosis 
elsewhere. 

The Phylogeny of the Head and Face, through the anthropoid 
ape and races of the world to the average type, is extremely interesting. 
In considering the head bend in man's flight from fish and reptile, to bird 
and mammal, it will be seen that the most extreme development in the 
head and face bend are to be observed in animals such as the camel, the 
cow, the horse and other mammals, including lower monkeys. In the 
higher apes and animals under domestication, the face, nose and jaws 



66 



DEVELOPMENTAL PATHOLOGY 



begin to shorten and degenerate for the benefit of the higher structures 
such as the brain. This change of the shortening of the nose and face is 
nicely illustrated in (Fig. 36) where the domestic pig is not required to 
root for a living. The arrest of the nose, face and jaws is not unlike that 




Figure 36 
Wild boar contrasted with modern domesticated pig (Darwin and after Darwin, Romanes). 
The marked contrast between these two animals nicely depicts the change in structure 
owing to use and disuse. 

of the human. The law of use and disuse is finely illustrated in these 
two extremes. The breeding of dogs with a short nose and short upper 
jaw from the wild wolf -like species are also examples. In natural selection, 
of course, this process goes on normally and sequentially (Fig. 37) in the 




Figure 37 
Evolution of the face from the anthropoid ape through the lower negro types to the ideal 
face of the Apollo Belvedere (Camper). 

phylogeny of the human race, but it requires a much longer period of time 
to produce the same results. 

The great anatomist and artist, Camper, in his physical observation 
on the difference of the features of the face considered in profile as the 
heads of apes, orang-outangs, of negroes and other peoples tracing up to 
antique heads, says, "y° u will be astonished to find among my plates two 
heads of apes, then of a negro and then one of a camel. " Dropping the 



A STUDY IN DEGENERATIVE EVOLUTION 67 

camel and beginning with the ape we find in order of phylogeny first the 
gibbon, second, the orang-outang, third, the gorilla so far as hand and 
foot are concerned, and the chimpanzee so far as brain is concerned, then 
the pithecanthropus, Neanderthal man, negro from the lower to the higher 
forms of face, and finally, through different races, until the ideal face of 
Camper, the Apollo Belvidere, appears. 

One of the most interesting stages in connection with Camper's 
illustration of the evolution of man from the lower animals is seen in the 
skull of the ape-man (pithecanthropus erectus), discovered by Eugene 
Dubois in Java in 1891-2. Fig. 38 illustrates the restored skull. 




Figure 38 
Restoration of the skull of the pithecanthropus erectus, about one-fifth natural size (Dubois) 

The brain cavity in this type is absolutely larger and, in proportion 
to the size of the body, much more capacious than in the Simiadae, yet less 
so than in the Hominidae. Cranial capacity is about two-thirds of the 
human average. Inclination of the nuchal surface (o) of the occiput is 
considerably greater than in the Simiadae. Dentition, although retro- 
gressive, is still the human type. The femur is equal in its dimensions 
to that of man, and, like man's, is adapted for walking in an upright position, 
higher than the Spy or Neanderthal femur, which are pithecoid. 

Of this skull, the upper portion alone is preserved, the line of fracture 
extending from the glabella backward irregularly to the occiput, which 
it divides somewhat below the upper nuchal line. The cranium seen from 
above is an elongated oval in outline, dolichocephalic, and is distinguished 
from that of other anthropoid apes by its large size and its higher arching 
in the coronal region. The greatest length from the glabella to the posterior 
projection of the occiput is one hundred and eighty -five millimeters; the 
greatest breadth is one hundred and thirty millimeters ; and the smallest, 
behind the orbit, is ninety millimeters. The cranium in its original condi- 



68 DEVELOPMENTAL PATHOLOGY 

tion must have been of somewhat larger dimensions. The upper surface 
of the skull is without ridges and the sutures all appear to be obliterated. 

This dolichocephalic skull, with an index of seventy degrees, is readily 
distinguished from the brachy cephalic orang-outang skull. The absence 
of the characteristic cranial crests separate it from the dolichocephalic 
skull of the adult gorilla. In its smooth upper surface and general form 
it resembles somewhat the chimpanzee skull and still more that of the 
gibbon (Hylobates). 

There are two or three points of interest which seem to indicate that 
this skull belongs to a type neither man nor ape. The first is the peculiar 
length and shape of the orbital ridges. If the animal had walked upon 
all fours, such prominent ridges would have been unnecessary for the 
protection of the eyes from the sun and violence of all kinds. They are 
much more prominent and thinner than those of the Neanderthal or Spy 
skulls. If he had walked continuously upon all fours the occipital protuber- 
ance and the superior curved line for the attachment of strong muscles 
would have been excessively developed. In the place of occipital protuber- 
ance appears a depression. 

The protrusion of the face and jaws, from the perpendicular line, is 
quite marked. The lower jaw is more human than ape-like, since it possess- 
es a well developed chin. The teeth are deeply set in the jaw, the crowns 
are short while the roots greatly diverge. 

Through the kindness of Dr. Whitney of Honolulu, Hawaii, I have 
in my possession an Hawaiian skull with like characteristics to the pithe- 
canthropus erectus. It is dolichocephalic, like the illustration, and has 
large orbital ridges. 

Ontogeny 

His distinguished three periods in the development of the unborn 
child. First, the product of conception during the first two weeks is called 
the ovum; second, from the third to the fifth week, the embryo; third, 
after the fifth week, the fetus. Until 1907, the earliest human ova was 
that described by Peters. In that year, J. H. Teacher, of Glasgow, 
Scotland, discovered the youngest known embryo. It antedates Peters' 
classical fifteen-day ovum by from one to three days. These can only be 
differentiated with the aid of the microscope. Fig. 39 represents the first 







Figure 39 
Early embryos (His). In the last illustration, which is at about the third week, the head 

bend begins. 



A STUDY IN DEGENERATIVE EVOLUTION 



69 



stage, that of the ovum from the primitive streak to that of an ovum four 
and two-tenths millimeters in length. In all of these illustrations, there 
is no head bend. This represents the fish and reptilian stage. In the last 
illustration, however, there is a slight head bend. 

Beginning with the third week (Fig. 40), the head bend is quite 




Figure 40 
Embryos from the fourth to the fifth week (His) . In these illustrations the head bend is most 

marked. 

marked which gradually increases as development goes on; the gill slits 
are well developed. In the embryonal period, the formation of the medul- 
lary groove and canal takes place. The abdominal pedicle is seem coming 
off from the tail end of the embryo. The embryo at this period is made 
up, in great part, by the yolk-sac. A little later, the double heart, (the 
fish stage) may be noticed, while the cerebral and optic vesicles, as well as 
the visceral arches and clefts appear. At the end of the third week, the 
limbs begin to make their appearance as small buds, not unlike those of the 
frog. At the fourth week, a great increase in the size of the embryo takes 
place. The eyes, nasal pits, maxillary processes, ears and nose are now 
visible. The oral fossa has assumed a somewhat irregular shape. A 
little later, the maxillary and globular processes unite and form the nasal 
pits, separating them from the mouth cavity. It is at this period (Fig. 41) 




Primitive 
oral cavity 



Lateral nasal process 

esial nasal process 
Maxillary process 
Mandibular process 



Figure 41 
Fetus showing development of the face and mouth at the twenty-seventh day (Piersol). 
It is at this period that on account of an unstable nervous system, the tissues are not 
properly formed, resulting in cleft palate and harelip. 



70 



DEVELOPMENTAL PATHOLOGY 



in fetal development, owing to disturbed nutrition, that the globular process- 
es occasionally fail to unite, on one or both sides, producing harelip or 
cleft palate. At about the fourth week, it is impossible to determine 
from the appearance whether the fetus be that of fish, reptile, bird or 
human. The fetus is still markedly bent upon itself. The visceral arches 
and clefts are the most prominent characteristics of its cephalic region, 
and indicate the fish-like character in its evolution. 

At the end of the second month (Fig. 42), the brain begins to develop, 




Figure 42 

Embryos from the second month (His). It will be noted in these illustrations that the 

head is gradually assuming the upright position. 

the head becomes considerably larger and more erect, and the fetus has 
passed its quadruped stage. The nose, mouth and ears are less prominent, 
and the limbs are more developed. The external genitalia are beginning 
to develop. At the end of the third month, the fetus and its entire product 
are about the size of the fist. Ossification has made its appearance in 
some of the bones. The fingers and toes are observable. Sex differentia- 
tion is now possible, but is not definitely revealed until the end of the 
fourth month. At the fifth month, the skin has become less transparent 
and the entire body is covered with downy hair. At the sixth month, 
fat begins to deposit. The head becomes more erect and assumes the posi- 
tion of the upright vertebrate. At the seventh month, there is very little 
change. At the eighth month, the skin is red and wrinkled. At the 
ninth month, the wrinkles disappear and the fetus has arrived at its full 
development. 



A STUDY IN DEGENERATIVE EVOLUTION 



71 



In the early stages of development, the skull is cartilaginous, like 
that of sharks and allied fish (Fig. 32), whose skulls always consist of 
cartilage impregnated with lime salts. In bony fish and amphibians, the 
overlying bones gradually bring about absorption of the cartilage in places. 
According to Sutton, much of it exists through the life-time of the animal. 
In the skulls of even the highest adult mammals, there are traces of this 
important matrix-tissue, characteristic of embryonic states. 

Embryology' of the Human Skull. The embryogenic (develop- 
mental) history of every mammalian skull is the same. If all the investing 
tissue be removed from the skull of a human embryo at the tenth week 
of intrauterine life, the base will resemble Fig. 43, A B C. 




Figure 43 
Four views of the human skull in its cartilaginous condition (Sutton). A, the skull viewed 
from above; F N P, fronto-nasal plate; S, orbit o-sphenoid; A C, auditory capsules; 
B, the same skull viewed from below; C, side view; F N P, fronto-nasal plate; E, Eusta- 
chian cartilage; M, Meckel's cartilage; S, styloid cartilage; D, section through the facial 
region of the same skull. 

Face, nose, jaws and base of the skull are cartilaginous in character. 
The primordial chondrocranium is excellently shown in these illustrations. 
This illustration shows the relationship between the human skull and the 
development of the chondrocranium of the lower vertebrates, especially 
the insectivorous mammals, pointed out by Minot in the phylogeny of the 
skull. Minot says, "the skull then is developed from two distinct skeletons, 
the primary cartilaginous skeleton, which in the higher forms becomes 
partly ossified, and the second skeleton composed of dermal bones. The 
cartilaginous stage is made up of separate cartilages, but no definite line 



72 DEVELOPMENTAL PATHOLOGY 

can be drawn between a previous stage and the following. The dermal 
bones begin to develop before the cartilages ossify, and are present in 
cartilaginous fish, hence they must be considered older than the bones 
replacing cartilage. The replacement of cartilage by bone is very slow 
and never becomes complete." 

Owing to the head bend of the embryo, the oral invagination, or mouth 
cavity, is brought between the forebrain and the heart upon the ventral 
surface. This is its permanent position in sharks. Through the vertebrate 
series, if the development of an amniote (reptiles, birds and mammals) be 
followed, an increase occurs in the region of the olfactory and oral invagi- 
nations, in consequence of which it projects more and more, and by a 
further throwing of the whole head upward (Fig. 42), the face is brought 
forward and projects in front of the brain. 

In the development of the skull, the chondrocranium is the first stage, 
formation of the dermal bones the second, and ossification of the primordial 
chondrocranium the third. The brain now passes through the different 
states of development described in Chapter III (Fig. 23), from fish to 
reptile and from bird to mammal. In this flight, the bones develop about 
the brain and pass through these stages (Figs. 44 and 45). In this fine 
collection and arrangement the student can readily trace the ontogeny of 
development. At the third month, calcification begins, as previously 
stated. Ossification commences at the center of each bone and proceeds 
toward the periphery. The bones are separated before birth by membra- 
neous intervals in which deposits of bone cells are deficient. The fetus is 
beginning to assume human characteristics by the anterior and posterior 
development. The gradual higher anterior development of the brain 
and skull is also quite noticeable. 

The human skull and that of the higher ape resemble each other at 
birth. From this period on (Fig. 16), the growth of man is centered in 
brain development. The animal type branches off to follow animal and 
physical instincts. The perceptive faculties of man are centered in the 
forebrain. 

There are still non-ossific remains of the membrane as observed in all 
the skulls up to and including three and one-half years of age. The font- 
anelles usually close during the first year. As will be observed, however, 
when there is a large deficiency, or when the bone deposits are slow, a much 
longer time is required. Not infrequently, these gaps are not filled by the 
original bone from the first centers of ossification. When this is the case, 
smaller bones (wormian) fill the deficiency. These small bones often 
develop from special centers of ossification. As has been shown in phylog- 
eny, the cartilaginous primary skull, being insufficient to cover the brain 
resulting in gaps, the osteogenic function, normal in certain edentates, 



A STUDY IN DEGENERATIVE EVOLUTION 



73 




Figure 44 
Fetal skulls in their evolution from the third month to birth (Charles Ward). The gradual 
development of the anterior part of the brain in phylogeny is here noticed. The changes 
are rapidly taking place in face and jaws. 



74 



DEVELOPMENTAL PATHOLOGY 




Figure 45 
Skulls in their evolution from birth to three years and six months (Charles Ward) . Showing 
still further evolution in frontal and face development. Arrests and excessive develop- 
ment of all the structures are outlined at this early period. 



A STUDY IN DEGENERATIVE EVOLUTION 75 

reptiles and bony fish, furnishes material (wormian bones) to fill these 
cavities. These bones are more frequently found in degenerates than 
elsewhere. Lombroso and Ferrero have recorded a number of cases 
observed in the crania of harlots and criminals. I have frequently seen 
these bones in degenerates, especially in those skulls, larger than normal, 
of which the hydrocephalic is the type. While these bones may develop 
in seemingly normal individuals, they occur with an unstable nervous 
system. Thus, for example, the hydrocephalic brains of Sir Walter Scott 
and Cuvier were repaired by an increased barren ependymal tissue. Healed- 
up hydrocephalous is often thus attended by a seeming normality which 
co-exists with wormian bones. 

The man whose skull is illustrated in Fig. 34 was a familiar character 
on the streets of Chicago for many years. He was forty -five years of age 
when he died, had always been a cripple with imperfectly developed and 
mis-shapen limbs. He wheeled himself about the streets in a little cart 
selling lead pencils. The history and description of this man by Hektoen 
and Parker are of unusual interest. The arrest of development of the face 
and the large number of wormian bones (of which there were one-hundred 
and seventy-two), together with the physical mal-development of other 
parts of the body, show a marked, unstable nervous system. 

The Processes of Skull Growth are far from simple. Skull and 
brain are interdependent. The cranial cavity has a much larger volume 
in the child than the adult. That the entire roof and a large part of the 
sides of the skull being composed of membraneous or dermal bones not in 
contact with each other, at birth, give an excellent opportunity for any 
change in skull or brain development. Even the skull base, at this time, 
has but little ossified cartilage. The general changes which take place 
in post-natal skull development, are first, a relative elongation of the 
anterior portion, and second, relative increase in the depth of the superior 
maxillae. 

If, in a child's skull, a division be made between the central points of 
the occipitals, the base of the skull will be divided into two portions of 
equal length. The frontal portion of a similar division in an adult is 
much greater than the back portion. Froriep has shown the proportion 
between the two is 5 to 3 in the adult, as against 3 to 3 in the child. This 
increase of the skull's frontal portion marks a rapid growth, associated 
with a relative increase in the dorso- ventral measurements of the superior 
maxillae. 

Development of the Face depends upon enlargement and fusion 
of the mouth and nose cavities, and upon later partial separation of nose 
and mouth and nose cavities, leaving the posterior nose open. It depends 
further upon the growth and specialization of the face region, of which 



76 



DEVELOPMENTAL PATHOLOGY 



elongation is the most prominent feature, and, finally, upon the development 
of a prominent nose. When the medullary tube of the notochord enlarges 
to form the brain, the end of the head bends over to make room for that 
enlargement (Fig. 30). The bending of the head carried the mouth plate, 
which is to be the mouth, over to the front of the head. What develops 
the mouth cavity is the growth of the brain and the increase in size of the 
heart cavity, which expand to the front, leaving the mouth cavity between 
them. The mouth cavity represents two gill slits united in the front line. 
The nose (Fig. 46) is formed from the two olfactory plates situated just 




Figure 46 
Reconstruction of the face (His). Embryo Sch. N. of, olfactory nerve; Nn, nasal cavity; 
R T, Rathke's pocket; Ch, notochord; T, tonsil; Pg, processus globularis; Gl, palate 
anlage; Uk, mandible. 



in front of the mouth and in contact with the forebrain. These olfactory 
plates grow in size by the increase in tissue and the resulting pits pass 
away from the brain. At first these pits, although separated by what is 
called the nasal process, communicated freely with the mouth. The 
nasal process includes the origin of the future nose and of the future inter- 
maxillary region of the upper lip. 

The nose and face of the lower vertebrates extend a considerable 
distance in front of the brain. This frontal development of the face is 
retained to a less and less extent as evolution progresses to the pithecoid 



A STUDY IN DEGENERATIVE EVOLUTION 77 

and anthropoid apes. In man, the face, including the nose, is quite short. 
The brain and skull cap cover the face. 

Struggles for existence between the various organs implies the existence 
of potentialities, which not only are inherited, but pass through periods 
when the newer type has to compete with organs already existing. There 
must, therefore, be the usual excess of material for growth, like that which 
occurs in fractures, where provisional callus is thrown out. This needful 
excess is obtained at the expense of other organs. If the utilization of 
disappearing fetal organs suffices to provide this, defects do not occur. If 
not, they occur along the line of least resistance, which may be the higher 
or lower gains. Thus, when the brain and skull do not receive the normal 
amount of nourishment, they remain undeveloped and the face and jaws 
become excessively developed. On the other hand, if the brain and skull 
receive the most nourishment, they become excessively developed and 
the face and jaws arrested. Fig. 34 shows an exaggeration of this law, 
owing to an unstable nervous system. The face, which was once larger 
than the cranium in this particular illustration, is very small as compared 
to the skull. The face, jaws and teeth become markedly deformed in 
every particular. 

Nose Development. The nasal pits proper are developed by the 
upgrowth of the ectoderm and mesoderm around the olfactory plate. The 
upgrowth takes place on the medial, upper and lateral side of each plate, 
and hence forms two pits with a partition (the future nasal septum) between 
them. These nasal pits communicate along their whole lower side directly 
with the mouth cavity. The nasal pit is at first very shallow. In their 
growth, there are two principal changes; first, growth of the tissues occurs 
around the olfactory plate, and then the pits migrate away from the brain. 
The nasal pits are separated by a projecting mass of tissue called the nasal 
process, which includes the partition between the two nasal chambers, 
the outline of the future nose and of the future intermaxillary region of 
the upper lip. The maxillary extends between the mouth and eye toward 
the nasal pit, and by joining the rounded end of the nasal process, begins 
the separation of the nasal and buccal chambers and completes the upper 
border of the mOuth. As development proceeds, the lateral ridge grows 
forward and covers in the nasal pit from the side forming the outline of 
the wing of the adult nose. These are now two external nares. The 
nasal chambers enlarge as the whole face enlarges and occupy an increasing 
space opening widely into the mouth cavity above the palate shelf. It 
is from the nasal pit proper that the so-called labyrinth of the nose is 
formed. The development Of the labyrinth begins with the appearance 
(during the third month of embryonic life) of three projec ting folds on the lat- 
eral wall of each nasal chamber. These folds are the upper, middle and lower 



78 DEVELOPMENTAL PATHOLOGY 

turbinal folds. They very early contain cartilage. The formation of labyrinth 
advances by formation of outgrowths, which become the ethmoidal sinuses, 
by the appearance during the sixth month of the antrum of Highmorii, or 
expansion of the nasal cavity into the region of the superior maxillary, and 
finally, by evaginations to form the sphenoidal and frontal sinuses, which, 
however, do not arise in man until after birth. The separation of the 
olfactory plate from the brain does not take place until the olfactory 
ganglion develops from the epithelium. The fibers lengthen, the olfactory 
and neural epithelium separate and, finally, the osseous cribiform plate is 
developed between them. 

The external nose develops toward the end of the second month of 
embryonic life by a growth of the nasal process. It is at first short and 
broad, having (at the third month of embryonic life) very nearly the shape 
which is permanent in certain negro races. The external nares and wings 
of the nose are carried forward with a general nasal growth. 

As soon as the external nose is separated from the mouth, there is a 
partition between the nasal pits and the mouth. The partition in which the 
intermaxillary bone is differentiated later is supplemented by another 
partition, the true palate, which shuts off the upper part of the mouth 
cavity from the lower, thus adding the upper part to the nose chambers. 
The palate is a secondary structure which divides the mouth into an upper 
respiratory passage and a lower lingual or digestive. The palate arises as 
two shelf -like growths of the inner side of each maxillary process, and is 
completed by the union of the two shelves in the median fine. These so 
arch as to descend a certain distance into the pharynx. In the pharynx, 
however, their growth is arrested, though they may be still recognized 
in the adult. In the region of the tongue which includes more than the 
primitive mouth cavity, the palate shelves continue growing. At first, 
they project obliquely downward toward the floor of the mouth and the 
tongue, rising between, seems in sections, which pass through the internal 
nares, to be about to join the internasal septum. As the lower jaw grows, 
the floor of the mouth is lowered and the tongue is thus brought further 
away from the internasal septum. At the same time, the palate shelves 
take a horizontal position and pass toward one another above the tongue 
and below the nasal septum to meet in the middle line where they unite. 
From their original position, the shelves necessarily meet in front, toward 
the lip first and unite behind, toward the pharynx later. In the human 
embryo, union begins at eight weeks and by nine weeks is completed for 
the region of the future hard palate, and by eleven weeks for soft also. The 
palate shelves extend back across the second and third branchial arches. 
The uvula appears during the latter half of the third month as a projection 
of the border of the soft palate. Soon after the palatal shelves have united 



A STUDY IN DEGENERATIVE EVOLUTION 79 

with one another, the nasal septum unites with the palate also, and thereby 
the permanent or adult relations of the cavities are established. 

The Jaws and surrounding tissues are developed from the three 
germinal layers of the blastederm in the following manner: From the 
epiblast, the epithelial lining of the cavity of the mouth and enamel of the 
teeth; from the mesoblast the jaws, blood vessels, lymphatics, connective 
tissue and dentine of the teeth; from the hypoblast, the epithelial lining 
of the alimentary canal beyond the oral cavity. 

The first indication of the formation of the oral cavity is seen very 
early in the life history of the embryo. The superior maxilla arises from 
three separate points; on either side of the embryonic head a process 
springs from the first pharyngeal arch. The processes pass downward 
and forward and unite with the sides of the nasal process. From the 
frontal prominence, the third process, the incisive, grows downward and 
fills in the space between the ends of the two preceding processes. By a 
union of these three processes, the superior maxillae are completed. The 
inferior maxilla is formed by buds growing from the first pharyngeal arch; 
these buds grow rapidly until union occurs at the median line. The 
central portion of the arch thus formed, very soon after the union of the 
lateral processes, becomes differentiated into a cartilaginous cord or band, 
which serves to strengthen the embryonic jaw. This is Meckel's cartilage. 
It is formed of two parts rising from the mallei of the ears and traversing 
both sides of the embryonic jaw to the point of union. While the jaw 
bone is forming, Meckel's cartilage disappears, by absorption; some author- 
ities believe it becomes ossified, forming part of the inferior maxilla. 

The face and jaws are lengthened by the development of the first and 
second dentition and also by the length in development of the rami. The 
alveolar processes lengthen to accomodate the jaws and the roots of the 
teeth. The roots and crowns of the temporary teeth, when in place, bring 
the jaws quite a distance apart. This lengthening of the jaws is consider- 
ably increased when the permanent teeth are in place. If, from any cause, 
the rami are excessively developed in length, the desire to bring the jaws 
together is restricted. The tendency is for the alveolar processes to 
develop upward on the lower jaw and downward on the upper jaw until 
the teeth occlude. 

Modification of the human face backward from the vertebrate type 
excellently illustrates degeneracy of series of related structures for the 
benefit of the organism as a whole. The progress of development of the 
vertebral face is checked in man because, as Minot remarks, the upright 
position renders it unnecessary to bend the head as in quadrupeds, and 
also because the enormous cerebral development requires enlargement 
of the brain cavity. This has taken place by extending the cavity over 



80 



DEVELOPMENTAL PATHOLOGY 



the nose region as well as by enlarging the whole skull. It is likewise 
because development of the face is arrested at an embryonic stage. The 
production of a long snout is really an advance of development, which 
does not occur in man. 

Types of Skull. Upon variation in the dermal bones depend, not 
only the race variations in skull and jaw types, but also variations produced 
by agencies acting on the individual during the periods of stress and by 
the degenerative influences on parents and child. Contrasting the human 
face, developed with that of animals with a long snout, apes and the lower 
negro type (Fig. 37), it will be seen that the jaws grow smaller in size and 
weight as the nterior brain development increases. Ontogeny, in the 




FlGURE 47 

Skull showing the jaws and face on the perpendicular line (original). This is the dividing 
line where normal development ceases and the pathologic begins in man's evolution. 

development of the human head, is now at the facial angle (Fig. 47), as 
represented in the last number of (Fig. 37) the Apollo Belvidere. 

Craniologists generally assume two prominent skull types, dolicho- 
cephalous (Fig. 48) , or long horizontally, that is antero-posteriorly, with 
long, narrow protruding jaws and the brachycephalous (Fig. 49), or approxi- 





FlGURE 48 

Dolichocephaly (Greves). 



Figure 49 
Brachycephaly (Greves) . 



mately round horizontally, with broad, square, non-protruding jaws. 
The two types are determined by the so-called cephalic index, which is 



A STUDY IN DEGENERATIVE EVOLUTION 81 

determined by the relation of the antero-posterior diameter (measured 
from the glabella to the farthest point of the occiput) to the transverse 
diameter from side to side. The former being taken at one hundred, the 
latter will range from about sixty to ninety-five or even more, increasing 
with the greater degree of brachycephaly and vice versa. Excluding 
artificial deformation, the extremes appear to lie between sixty-one and 
nine one-hundredths (Fijian measured by Flower) and ninety-eight and 
twenty -one one-hundredths (a Mongolian described by Huxley). 

In the evolution of races, both extremes tend gradually to approach the 
medium type of head, or mesaticephaly, with gradual recession of the jaws. 

Summary 
Phylogeny 

The head and face development from the single, as well as compound 
cell organism, is the most interesting of all the structures of the body. 

The bony framework of the head is developed partly from the vertebrae 
and partly from the dermal bones, which forms the armor of the skin, 
and acts as a protection for the brain. The earliest appearance of the 
skull in biology is seen in the lancelet, whose head end of the spinal cord 
grew in size and the cartilage correspondingly developed to protect it. 
Later, another skull developed from the dermal bones, so, according to 
Minot, there are really two skulls, originally separate, which united during 
the process of evolution. 

The primary skull, or chondrocranium, is a vertebral extension and 
sends outgrowths to cover the brain. Owing to brain increase, the chondro- 
cranium is not able to cover it, hence gaps result, called fontanelles, which 
are larger and larger, the higher one goes in the scale of life. These gaps 
are filled by dermal bones and, during the process of ossification, the union 
becomes so indistinct as to appear as but a single bone. Sometimes this 
union does not occur at all, and a suture remains during the entire life of 
the individual. Such openings are a mark of degeneracy, and constitute 
a reversion to the lower mammalian type. 

In man's development through fish, reptile, bird and mammal stages, 
extremes are observed and man's upright position is really a degeneration. 
Owing to disuse, man's face, nose and jaws are shortened and degenerate 
for the benefit of the brain. This is nicely illustrated by Camper in his 
profile study of apes, orang-outangs, negroes, to the Apollo Belvidere. 

Ontogeny 

According to His, there are three periods in uterine development; 
first, the product of the first two weeks is known as the ovum ; from the 



82 DEVELOPMENTAL PATHOLOGY 

third to fifth week, the embryo; third, after the fifth week, the fetus. Up 
to the beginning of the second month of fetal life, no distinction can be 
observed between fish, reptile, bird or mammal. At the close of the 
second month, however, the brain begins to develop and the human fetus 
passes from the quadruped stage. 

In fetal skull development, the chondrocranium is the first stage; 
dermal bone growth, the second, and ossification of the primary or chondro- 
cranium, the third. 

The skull of man and that of the higher apes resemble each other at 
birth, but after this period man 's growth is dependent upon his brain growth. 

During healthy human skull growth, the fontanelles usually close 
during the first year, but sometimes these are not filled by the original 
dermal bones and the osteogenic function furnishes the material. This 
material is called Wormian bones after Claus Worm. This is a degenerate 
condition often observed with hydrocephalous. 

Face development depends upon the growth and union of the mouth 
and nose cavities, their partial separation, elongation and the formation 
of a prominent nose. 

In the process of development, struggles for existence occur between 
the skull and brain on the one hand and the face and jaws upon the other. 
During this struggle, if the face and jaws receive the most nourishment, 
they become excessively developed, while the brain and skull remain 
undeveloped and vice versa. 

The external nose develops at the second month of fetal life and is 
short and broad. As soon as it separates from the mouth, a partition 
arises between the nasal pits and the mouth. The intermaxillary bone 
contributes another partition, the palate, which divides the mouth into the 
respiratory passage and the digestive. 

The oral cavity develops early in embryonic life. The superior 
maxilla is formed from a union of three processes. The inferior maxilla 
from buds from the first pharyngeal arch. 

The face and jaws elongate by the development of the deciduous and 
permanent teeth and also by the length of the rami. The alveolar pro- 
cesses also lengthen to aid the jaws and roots of the teeth. 

There are two generally recognized skull types, the dolichocephalic, 
or long head with long, narrow jaws and the brachy cephalic, or round head 
with broad, square jaws. However, owing to intermixture of races, 
intermarriage, environment, these two types are slowly approaching the 
mesaticephalic or medium type, with jaw recession. 



Chapter VIII 
PERIODS OF STRESS 

MAN'S embryonic history essentially involves that of the inverte- 
brates as well as the lower vertebrates. In his embryo differenti- 
ation, as we have seen, structures are developed and others 
sacrificed for the benefit of the organism as a whole. This economy of 
growth likewise governs the relation of the organs to each other. 

Development of the organism involves changes in which certain 
parts, some organs for instance, cease to advance after certain periods, 
while others assume a relatively greater importance. Some of the func- 
tions, possessed at the beginning by certain cells, are lost, and they develop 
in one direction only. These changes, while they fit the cell to perform 
its specific purpose in the organism, involve a loss of power of independent 
existence and are, in this respect, expressions of excessive and arrested 
development respectively, either of which constitutes degeneration. 

Similarly, certain organs well developed in early life, undergo arrest 
of development or degenerate as the organism advances, cease to grow 
and even disappear. The organism as a whole is itself limited in its periods 
of growth, for, after it has reached a certain age, it ceases to increase in size 
and remains practically stationary throughout life. Growth of the organ- 
ism is regulated by the activity of certain ductless glands, the pituitary 
gland for instance. Whatever organ may check or stimulate growth, 
it is certain that when it fails and an undue or under size is attained, 
pathologic conditions result of excessive and arrested development. 

During man's development from the primitive cell, certain periods 
occur in which unfavorable influences so act as to occasion a stress or 
struggle. These are known as periods of stress. A period of stress is 
when a new function disturbs the physiologic balance previously existing. 
Stress results from the organism having to accomodate itself to the dis- 
turbance. An example is the onset of menstruation in the girl and its 
disappearance in the woman. The stress may act on the organism, as a 
whole, or on a particular part. If the stress be upon the organism as a 
whole, the organs least able to bear it show its effects most clearly. Thus, 
partly developed organs, whose functions are as yet imperfectly established, 
are likely to be checked entirely in their development or to take an abnormal 
course. The organs of greatest importance may secure nourishment and 
nervous force at the expense of others, so that there is a struggle for existence 
between the different organs. If the stress fall on one part, local changes 

83 



84 DEVELOPMENTAL PATHOLOGY 

may result in arrested or excessive development, that is, in degeneration 
of the particular organ. These changes will be more marked if the stress 
occur during the plastic state of the affected organ, but on the other hand, 
under such conditions reparative changes are apt to be correspondingly 
active. 

Degenerative Influences. Three kinds of unfavorable influences 
affect the organism or its parts, viz: — mechanic, toxic and nutritive. 

Mechanic Influences are frequently operative in changing the 
direction of the development of certain organs. Thus the weight of the 
body may operate in certain infants producing deformities like bow legs. 
Mechanic influences are often effective in changing the shape of the jaws 
and teeth. A mechanic influence, ordinarily insufficient to produce an 
abnormality, may do so at a period of stress when it is favored by weakness 
from other causes. 

Toxic Influences. The germ of disease may be inherited, or general 
nutrition of the fetus may be so checked in development that the child 
inherits a predisposition to disease. 

Through this check to fetal development, the phagocytes, or white 
blood cells, become so weakened that they are unable to devour fetal 
structures, as useless to man as the tadpole's tail (which it devours) is 
useless to the developed frog. This power being weakened, the organs 
which form antitoxins (or protective tonics against disease), from lack of 
development fail to perform their function. For this reason, in the degener- 
ate, many infections and contagions assume their old destructive type. 

The influence of these disorders in the parent may result in the bony, 
mal-development shown to occur in animals by Charrin and Gley, and in 
man, by Coolidge. The facial bones, jaws and teeth are peculiarly liable 
to be thus affected. Though the effect of the disease on the parent be but 
temporary, the child's development may be checked as to higher tendencies. 
Thus mothers have borne moral imbeciles, epileptics or lunatics after a 
pregnancy during which they were attacked by a contagious disease, 
albeit the children of subsequent and previous pregnancies were normal. 
Marked deformities were the result. 

The children of pregnancies previous to the one complicated by the 
contagious disease or tonic elements may be healthy, while those of subse- 
quent pregnancies are defective. Any contagious or infectious disease 
may not interfere temporarily with the bodily strength, but may produce 
complete change in the parent's system, extending even to the highest 
acquirement of man. 

Nutritive Influences (the most common) take place in two direc- 
tions: either in an excess of nutritive material which, when the proper 
conditions are present, leads to excessive development (Fig. 34, skull) of 



A STUDY IN DEGENERATIVE EVOLUTION 85 

the affected parts, or conditions are unfavorable to nutrition and arrested 
development also (Fig. 34, face and jaws) occurs. The conditions unfavor- 
able to nutrition are, lack of nutritive material, lack of proper assimilation 
and lack of proper nervous influences to stimulate and control nutrition. 

Periods of stress during development are called periods of evolution; 
those after maturity, periods of involution. At these periods of stress, 
development of the nervous system may be strained and produce arrests 
or excesses in development or degenerations. 

Arrests or excesses occurring at any period during development 
underlie all so-called deformities of the body. These are often reversions 
which simulate features of the adult fish, reptile, bird and mammal, 
characteristic of the fetal stages through which man, reproducing his 
phylogeny in his ontogeny, passes. The structures most prone to such 
degenerations are the head, face, nose, jaws and teeth, since these feat- 
ures are still in process of evolution and they are therefore peculiarly 
susceptible to the law of economy of growth in the struggle for existence 
between organs. This struggle between organs occurs among animals 
as well as in man. Wild animals in captivity, and others through 
domestication (change of environment and food), present changes in 
structures similar to those of man. 

Structures undergoing degeneration are, because of greater or lessened 
blood supply, more liable to disease than those more highly evolved. 
Marked illustrations of this may be found in irregularities of the teeth, 
in disharmony in jaw development where the teeth are not being lost fast 
enough for the receding jaws, in interstitial gingivitis, and in excesses and 
arrests of development of the structures of the nose and sinuses. 

Periods of Stress. Struggles for existence on the part of the 
different organs and systems of the body are most ardent during periods 
of evolution and involution. During development in utero, during the 
first dentition, during the second dentition (often as late as the thirteenth 
year), during puberty and adolescence (fourteen to twenty-five), during 
the climacteric (forty to sixty), when uterine involution occurs in woman 
and prostatic involution in man, and finally, during senility (about sixty 
and upwards), mental or physical defects may occur, a congenital tendency 
to which has remained latent until this period of stress. 

When systemic balance, the rational attendant of evolution, is disturbed 
by change in environment, the organs do not pursue their normal 
growth. Such disturbances are most apt to occur during periods of stress, 
because of the varying relations of different organs. 

The first intrauterine period of stress occurs during the early third 
of embryonic life, when the embryo rapidly passes through the stages 
which correspond to the adult fish, reptile, bird and mammal types and 



86 DEVELOPMENTAL PATHOLOGY 

assumes the form of the future human being. In this period, the most 
marked deformities occur, and monstrosities are produced which often 
result in the death of the fetus. Such disturbances in development are 
likely to affect most powerfully, structures in which evolution is variable. 
This influence must strongly affect nutrition of the dermal bone elements 
of the skull, face, nose and jaws, and hence must affect the teeth. Its 
results are not always obvious until the later periods of stress. 

A check on or an excess of the growth of the higher organs of the 
nervous system frequently results in impairment of the mental faculties 
in that any of the degenerations may occur. In these cases, the brain 
remains in the stage characteristic of the common simian ancestor, or the 
higher faculties may attain only the development of primitive races, in 
whom emotional control and ethical ideas are insufficient to meet the 
exigences of civilized states. Together with and dependent upon this 
cerebral mal-development, deformities of all the structures of the body, 
including the head, face, nose, jaws and teeth occur. 

In the latter part of intrauterine life, imperfect development of the 
nervous system may be accompanied by a premature growth of the teeth, 
so that they may erupt before or at birth. Prenatal or congenital teeth 
often accompany imperfect development of other organs. 

The intrauterine development of man and ape is so similar that they 
congenitally resemble each other more closely than do the developed 
adults. The fetus of the ape resembles an adult more nearly than the 
adult ape resembles the adult man. In extrauterine development a 
marked contrast exists. The ape passes through a short infancy to a 
condition of fixity from which there is no further development. 

Periods of stress are furnished by the different periods of embryonic 
as well as by those of extrauterine development. Even sex is determined 
by conditions of stress after a certain period. Poor maternal nutrition 
will determine an excess of males, while good will determine an excess 
of females. Arrests at certain periods of intrauterine life will produce 
prematurely senile states; since, as already stated, there is a period of 
intrauterine life during which the fetus wavers between the senile appear- 
ance of adult anthropoid apes and that of mankind in youth. This 
intrauterine stress may be an expression of the general nervous exhaustion 
of the mother, which, first affecting the check influences of the central 
nervous system, finally leads to unchecked excessive functionation of the 
part of the local nervous systems of the various organs, secondarily leading 
to their exhaustion. In consequence, the mother is unable either to 
manufacture proper elements of nutrition or to properly excrete waste 
material. The fetus, thereby starved and poisoned, fails to pass through 
the periods of stress in a complete, well-balanced manner. The stress in 



A STUDY IN DEGENERATIVE EVOLUTION 



87 



these periods is naturally strongest on those structures which are transitory 
and variable in type. This influence may, furthermore, be exerted on 
the fetus by virtue of stress, mental or otherwise, in the mother. The 
human fetus exhibits, as elsewhere shown, very decided re-action to sensory 
impressions on the mother. 

The Fetal Periods of Stress in the human organism deserving 
most attention are those occurring at sex differentiation and at the senile 
or simian period (Fig. 50) of intrauterine life, about four and one-half 




Figure 50 
Fetus, fourth month (original). This is the senile or simian type. An arrest of development 
at the first period of stress. The wrinkled face; the hairy body; the arrest of the ear 
and the nose; the flabby skin; the long, slender fingers; the arrest of muscles; the long 
flat feet show the permanent arrests of children born of parents with unstable nervous 
systems. 



months after conception. Three conditions, infantilism, masculinism, and 
femininism, and occasionally a mixed state, result from arrest of develop- 
ment before, at, and after sex differentiation in intrauterine life. As sex 
organs and sex nerves are differentiated before the sexual appetite appears, 
the mental side of sex can be determined only in extrauterine life. Practi- 
cally all three conditions mentioned are arrested development of the 
promise of the child type. 



88 DEVELOPMENTAL PATHOLOGY 

As the female type most nearly approximates, from the stand-point 
of bodily and nervous development, the promise of the child type, checks 
or excesses in its development result in masculinism. In the first the 
female has proceeded so far in development as to have female organs and 
their functions, while retaining traces of the lower male type. In the 
second, the male has proceeded along the line of evolution toward the 
female type, but ere sex has been fully differentiated, further development 
is checked and the male type is finally assumed as the predominant one. 
Both sexes proceed from an indifferent type, nearly resembling the herma- 
phroditic type found in the lower animals. Arrest of development takes 
place at any point in the embryogeny. Arrest at these periods of stress, 
through any process which retards development, peculiarly influences the 
development of the child after birth. When due to syphilitic conditions, 
which exert a severe strain on development, the child readily succumbs 
to the infections and contagions. It also produces early senile stress in 
the child so important as regards the head, face, nose, jaws and teeth. 
Forces exerted during the senile period of stress play a large part in deter- 
mining precocity and its product premature senility, with osseous and 
other consequences. Neurasthenia in the parent may result in bony 
arrest or excess of development, such as is shown in macro- and micro- 
cephalic heads. The head, facial bones, nose, jaws and teeth are peculiarly 
thus affected. If the effect of disease on the parent be but temporary, 
one child's development may be checked as to higher tendencies while 
another may show no such defect. 

The power of passing through the fetal periods of stress depends on 
the condition of the fetal organism at the time of the periods of stress. 
This condition depends partly on inherited factors and partly on maternal 
conditions. Defect in either, at this period of stress, may so affect the 
struggle for existence between the fetal organs that reversionary conditions 
gain the ascendancy. This is true of such conditions as cyclopia, in which 
the pineal body becomes an actual eye, as in certain lizards, while the 
paired embryonic eyes in man disappear. Similar stress at the proper 
period causes arrested brain types in idiots, at the stages resembling the 
brains of sauropsidae (bird and reptilian types). 

To a certain extent, periods of stress resemble ancestral stages. More- 
over, when there is a recapitulation of ancestral stages it often happens 
that evolution takes place without leaving traces of the various stages. 
This is especially the case in complex organs which have been produced 
by many lines of evolution converging in a single structure — a structure 
which thus becomes the seat of a special function or set of functions. 

Extrauterine Periods of Stress. During the whole developmental 
periods of man, extending over the first thirty years of his life, marked 



A STUDY IN DEGENERATIVE EVOLUTION 89 

changes in the nervous system and associated organs occur. There is a 
constant demand on the powers of nutrition. During this period, vegeta- 
tive life undergoes several marked changes. Thus are produced what may 
be called the post-natal periods of stress. The first period of infancy is 
comparatively uniform and extends to the eruption of the temporary 
teeth, which marks the beginning of the post-natal or second period of 
stress. During this period of infancy, disturbances are seldom met with, 
if the infant be properly protected. The food is introduced in a practically 
sterile condition from the mother's breast. In the absence of infections, 
the respiratory and circulatory apparatus act normally and growth is 
uninterrupted after the first normal decrease in weight. 

With eruption of the temporary teeth, begins the second period of 
stress. This event involves a series of changes which occupy the time 
from six months to two years after birth, and are almost as remarkable 
as the changes occurring in the early weeks of intrauterine gestation. 

During this period, the digestive organs assume more complex func- 
tions. Teeth prepare the solid food. The intestinal canal becomes 
accustomed to the presence of normal micro-organisms and prepared to 
resist the invasion of injurious germs; urination and defecation become 
subject to voluntary control and restraints of decency. Power to stand 
upright and to walk is attained. The faculty of speech is developed. At 
this period, deformities of the head, face, nose, jaws and teeth are seen. 

The second dentition, beginning with the sixth year, forms the third 
period of stress. Here deformities of the head, face, nose, jaws and teeth 
are more noticeable. 

The fourth is ushered in by puberty at which time the generative 
organs begin to be functionally active. Marked changes occur in the 
mind and nervous system at this time. The osseous system reaches its 
complete development at the close of adolescence and the organism in 
general assumes actable condition, which it maintains without apparent 
change throughout adult life. 

The climacteric, occurring in women at about the fifth decade, and 
the failure of sexual powers in man somewhat later, necessitates re-adjust- 
ments of metabolism of great importance to all organs. This may be 
called the fifth period of stress. 

Lastly, there is the period of decadence and senility in which the 
unity of the organism is indicated, not by the preservation of all in full 
vigor, but by the economy with which the failing resources are applied to 
the maintenance of vitally necessary organs to the detriment of those 
whose functions are less essential. In this period, the teeth are liable to 
soften and to be lost as a result of interstitial gingivitis and are not replaced ; 
the jaw atrophies and similar changes take place in other parts of the 



90 DEVELOPMENTAL PATHOLOGY 

body. It is difficult to separate, at this period, the essential effects of 
failing nutritive power from the results of disease. Could he be protected 
from the inroads of disease, which must materially modify the natural 
process, man would degenerate and die in a different way from that com- 
monly observed. Premature senility may evince itself in atheroma of 
the arteries at the periods of extrauterine stress. This has been observed 
frequently in children of vegetarians, and after fevers. 

Owing to the struggle for existence, which occurs at puberty, between 
the old type of the chondrocranium and its new type as supplemented by 
the dermal bones, the nervous system may take a distorted ply and arrest 
bodily, nervous and mental development, so that body and face remain 
at the childish point; or the body and nervous system are checked; or, 
finally, the nervous system of certain organs alone are checked, while the 
body goes on to full development. Not infrequently, the face is arrested 
at any period from birth to puberty. Hence many persons retain a youth- 
ful appearance through life. 

Heredity and Atavism. The questions involved in heredity and 
embryonic development as concerned in mal-development are by no means 
so simple as the average practitioner assumes. As previously stated, at 
the outset, all vertebrate embryos assume the same type before definitely 
differentiating into their final type. Arrests of development, hence, produce 
conditions found in lower types. Some arrests may be for the benefit of 
the body as a whole, while others are an arrest of the type. There is a 
struggle for assimilable nutriment between the different structures of the 
embryo. 

Nature is "careful of the type but careless of the single life. " Heredity, 
therefore, tends most thoroughly to preserve the type, and here heredity 
is aided by atavism. Throwbacks (atavisms) preserve the most recent 
type against gains or losses from heredity of parental characteristics. 
The single life represented by the parent leaves but a slight impress com- 
pared with the influences which have made the human type as distinct 
from the lower types. The single life of the parent may improve or deface 
the type as represented in him or her, at adolescence or, later, during the 
period of reproductive activity. 

Atavism (or throwback) does not always "drag evolution in the mud," 
for throwbacks tend to preserve the human type at the expense of the 
parental gains or losses. Either gain or loss may be attained at the expense 
of that balance which, through the great law of conservation and correla- 
tion of force, constitutes strength. The possible gains of a type foreshadowed 
in the child are, for this reason, never fully realized in the adult (Fig. 51). 
The child is not an undeveloped man, but man is an imperfectly developed 
child. The human infant presents, in an exaggerated form, the chief 



A STUDY IN DEGENERATIVE EVOLUTION 



91 



distinctive characteristics of humanity — the large head and brain, the 
small face, the hairlessness, the delicate, bony system. The child has not 
only these higher characteristics but a better liver, heart and lungs. As 




Figure 51 
The contrast between the prophecy of child development and adult fulfilment (modified 
from Havelock Ellis). The central figure, the child, shows a relatively large head; 
large belly; short and fat limbs. The picture to the left shows the man as a grown up 
child. If the brain should develop in proportion to that of the child, man would become 
a much greater factor in the world. Figure to the right shows the normal developed 
man. Brain, liver, lungs, kidneys and body have been sacrificed for the benefit of the 
limbs. 

has been well said, he is all brains, chest and belly. With growth into the 
adult, these organs not only cease to develop, but are relatively sacrificed 
to the bony system, a loss probably better adapted to environment, but like 
the greater loss in the adult apes and lower races, a growth in senility and 
degeneration. Did environment favor the retention of the high type, 
foreshadowed just as described in the child, the genius type would be the 
rule, not the exception. 

Through type heredity and atavism, the individual is thus sacrificed 
for the race. Reproduction is a race characteristic and to it, as Herbert 
Spencer has shown, higher possibilities of the individual are often sacrificed. 
Immediate heredity would imply defect if it were not usually more than 



92 DEVELOPMENTAL PATHOLOGY 

compensated for by type heredity and immediate atavism, which reverts 
to higher ancestral types. In this way, embryonic types, from defective 
heredity persist after birth. The cyclops, with its primitive face and nose, 
is an arrest of development at the embryonic time when the pineal body 
was equal in possibilities as an eye with the bi-lateral eyes. Maternal 
environment or its reverse may exercise an enormous influence on embry- 
onic development in the direction of arrested or progressive evolution. 
Maternal shock produces arrests of development which are not photographic 
impressions, but survivals of embryonic states. While maternal impressions 
do have an affect, as before stated, it is in conditions of arrest, and not in 
photographic reproductions of the alleged cause of the impression. There- 
fore, at periods of stress, some structures disappear and others develop. 

The question whether degeneracy or pathologic factors be malign 
turns on how the structures affected stand toward the complete develop- 
ment of the individual. The structures of the face, as Mi not has shown, 
are, in man, degenerate as viewed from the vertebrate type. They are 
structures which, quite early in evolution, have been sacrificed to the 
gains of the central nervous system. On them, therefore, struggles for 
existence between organs at the periods of stress leave most decided 
marks. 

One of the phases of stress which result from the sacrifice of brain, 
chest and abdominal organs to limbs and bone is a nutritive one. Nutri- 
tive stress occurs very early with the change from placental nutrition to 
mammary. The child's organs, immediately after birth, work badly and 
a decrease in weight results. The relative loss in lung states, in liver, 
kidney and pancreas interfere with proper oxidation as much as does 
the relative loss of brain bulk interfere with proper inhibitory powers 
during the periods of stress. Among one of the results of this is premature 
obesity, a nutritive expression of stress particularly noticeable at the 
second dentition and at puberty. 

According to Fere, puberty lipomatosis (first noticed by Cruveilhier) is 
an expression of nutritive stress at the periods of evolution. It usually 
occurs in the descendants of instabilities or in the children of mothers 
who have been under strain during pregnancy. It is attended by great 
liability to disease and a marked tendency to systemic weakness when 
under morbid influence. These children are peculiarly liable to rheuma- 
tism, gout, etc., and great hemmorrhages from slight causes. Liver 
lipomatosis is often associated with precocious maturity and resultant 
early senescence (senility) . Very often it co-exists with protracted infantil- 
ism. Ninety-two per cent, of lipomatosic children examined by me had 
deformed ears to a marked degree. Sixty-six per cent, had arrested 
development while twelve per cent, presented excessive development. 



A STUDY IN DEGENERATIVE EVOLUTION 93 

In eleven cases where the child was too young to determine jaw character, 
the molars, incisors, cuspids, and bi-cuspid were present. Eighty- 
seven of the total number examined had arrested development of the 
upper jaw. Twenty- two per cent, had arrested development of the lower 
jaw. Sixty-four per cent, had V-shaped or saddle-shaped dental arches 
or their modifications and protruded teeth. Seventeen per cent, had 
hypertrophy of the alveolar process. Eighty-three per cent, were micro- 
donts. Twenty-seven per cent, had extra tubercles upon the molars. 
Eighty- two per cent, had more or less marked stenosis of the nasal cavity. 
Thirty-six per cent, had deflection of the nasal septum to the left and 
twenty-nine per cent, to the right. Twenty-one per cent, wore glasses for 
eye defects. In fifty-eight per cent, the thyroid gland was enlarged and in 
seven per cent, it was arrested in development, both conditions compat- 
ible with hypothyroidism. In two hundred and ninety-six cases of puberty 
with lipomatosis (one hundred and eighty males and one hundred and 
sixteen females) reported by Kiernan, there were ten cryptorchids, six 
hypospadiacs and three cases of pseudo-hermaphroditism. Three females 
had infantile bifid uteri; four enlarged clitorides; in one of these, the urethra 
perforated the clitoris as in the female shrew. Of forty girls who had 
reached the age of eighteen, only three menstruated normally. The others 
were amenorrhoeic or dysmenorrhoeic (of whom one-half had membraneous 
dysmenorrhoea) or had neurotic storms during the period. Sexual appetite 
anomalies were exceedingly frequent. There were one hundred and sixty 
hebephreniacs, ten cyclothymiacs, thirty acute cases of insanity, ten 
epileptics, fifteen hysterics and thirteen choreics. Ninety-seven had 
difficulty in learning to speak and thirty always stuttered. Other general 
nervous instabilities were present to an equal degree. 

Degenerate Children early manifest decided neurotic excitability, 
and tend to neuroses at physiologic crises like the first and second dentition 
(second and third periods of stress) and the onset and close of puberty 
(fourth period of stress) . Slight physical or mental pertubation is followed 
by sleeplessness, delirium, hallucinations, etc., there is hyperesthesia and 
excessive re-action to pleasant or offensive impressions; vasomotor instabil- 
ity is present; pallor, blushing, palpitations or precordial anxiety result 
from trivial moral or physical excitants. Precocity or abberation of the 
sexual instinct often occurs. Psychic pain arises from the most trivial 
cause and finds expression in emotional outbursts. Sympathies and 
antipathies are equally intense. The mental life swings between the 
periods of exaltation and depression, alternating with brief epochs of 
healthy indifference. Egotism is supreme and morality absent or per- 
verted. The latter condition is often concealed under the guise of moral 
superiority, religiosity or cant. Vanity and jealous suspiciousness are 



94 DEVELOPMENTAL PATHOLOGY 

common; intellect and temper are exceedingly irregular. Monotonously 
feeble, scanty ideation passes readily into seeming brilliance, even to the 
extent of hallucinations, but ideas are barren, as a rule, because generated 
so rapidly as to destroy each other ere they pass into action. Energy 
fails ere aught can be completed. The inability to distinguish between 
desires and facts produces seeming mendacity. The will, in its apparent 
exuberance, its capricious energy and innate futility, matches and distorts 
the one-sided talent or whimsical genius which may exist. The whole of 
this mental state may not be present. The tendency to introspection, to 
morbid fear, to gloom, to hallucinations, to alternations of depression and 
exaltation, may occur in a degenerate child in whom has been otherwise 
preserved that secondary ego, which is the latest and greatest acquirement 
of the race. 

Among signs of fatigue, especially at the second period of stress, is 
the slight amount of force expended in movement, often with asymmetry 
of balance in the body. The fatigued centers may be unequally exhausted; 
spontaneous finger twitches like those of younger children may be seen, 
and slight movement may be excited by noises. The head is often held 
on one side; the arms, when extended, are not held horizontally and usually 
the left is lower. The face is not necessarily evidence of bodily nutrition, 
as it may be well nourished, yet the body be thin. Three per cent, of the 
school children are below par in nutrition. They are of low constitutional 
power. They tend to an ill-nourished condition under the stress of life 
and, in many cases, to mental excitement which, while rendering them 
sharper mentally, militates against general nutrition. 

School strain produces, like all the acquired factors of degeneracy, a 
systemic nervous exhaustion which may be expressed either in general 
neuropathy or hysteria after puberty or in the trophoneuroses, like gout 
and allied states, or in epilepsy or arterial change, predisposing to rupture 
of arteries at periods of stress with resultant convulsions and paralysis. 

Defects of nutrition, due to an unstable nervous system, either in the 
parents or child or both, are therefore most demonstrable at the periods 
of stress. 

Having considered the periods in the life of man when the great 
departures in structure from the normal take place, we will now consider 
the causes which are instrumental in bringing about these changes. 

Summary 

The ontogenetic development of man reiterates invertebrate and 
vertebrate types, and, in the process, structures and organs are lost and 
modified for the benefit of the whole organism. Writers on the subject 



A STUDY IN DEGENERATIVE EVOLUTION 95 

all recognize this law, differing only in their wording of it. Aristotle 
called it the "law of economy of growth," whereby an organ or structure 
is lost or modified for the benefit of the organism as a whole; Lucretius 
showed, long ago, how the strongest survive and the weak are laid low for 
the "survival of the fittest"; Lamarck spoke of the "use and disuse of 
structure"; Darwin, harmonizing all of these concepts, called the principle 
"natural selection," and Osborn, in the study of animals, the "law of 
compensation." 

In man's development from the primitive cell, certain unfavorable 
influences create a stress or struggle between parts. 

A period of stress is a disturbance of physiologic balance. The 
development of new structures and the loss of others make necessary a 
systemic re-adjustment through the co-ordinating influence of the central 
nervous system. In pregnancy, for example, although it is temporary 
and regarded as physiologic, the system has to re-adjust itself to the new 
state of affairs, and it is, therefore, a period of stress. 

Periods of stress act upon the organism either as a whole or in its 
parts. Three chief kinds of influence, mechanic, toxic and nutritive, 
produce irregularities or degenerations in cell or organ development, and 
these deviations take the form of either arrest or over development of the 
evolutional types of structure that prevail at the time of stress. 

Periods of stress occurring during development are periods of evolu- 
tion; those occurring after maturity, periods of involution. 

Periods of stress are intra and extra uterine. The first intra-uterine 
period of stress is the early third of embryonic life, when structures are 
being differentiated, and this is the period when the most marked deformi- 
ties occur. The embryonic points of stress which call for greatest 
attention are the time of sex differentiation and the simian (senile) 
period. Extra-uterine periods of stress are first and second dentition, 
puberty and adolescence, climacteric and senility. The observable effects 
of intra-uterine stress are not always seen until long after birth — often 
they come out under the influence of some extra-uterine stress. 

The power to pass unscathed through fetal periods of stress depends 
upon the condition of the fetus at the time, and this, in turn, depends upon 
inherited and maternal conditions, especially the latter. Defect in either 
leads to arrest or over-development of organs or parts which correspond 
to the stage of development prevailing at the time. 

Periods of stress affect most strongly the variable elements of the 
organism, especially the brain and nervous system, upon whose proper 
development all of the parts and organs of the body depend for their 
normal growth and functionation; and it is in this indirect way, through 
the nervous system, that most body degenerations are brought about. 



96 DEVELOPMENTAL PATHOLOGY 

The questions involved in heredity are thus not nearly so simple as is 
commonly supposed. The direct influence of heredity, operating through 
the individual parents, and the wide influence of phylogenetic development, 
acting through atavism (reversion to lype), continually re-act upon each 
other in the offspring to preserve that wholesome balance which constitutes 
strength. For this reason the promise of the type, foreshadowed in the 
infant, is never fully realized in the adult; and in this way the steady, 
constant progress of phylogenetic evolution is insured. Thus, considered 
as a whole and from the standpoint of the race, periods of stress and their 
resulting degeneracies are all factors in the evolutional process. It is only 
from the individual standpoint and in the more extreme cases that degener- 
acies call for the interference of the physician. 



Chapter IX 

AN UNSTABLE NERVOUS SYSTEM THE CAUSE OF NUTRITIVE 

DISTURBANCES 

Checks on Excessive Action not Properly Developed 

BEFORE proceeding with the study of an unstable nervous system 
and checks on proper development, a clear understanding of the 
law governing arrest and excessive development must be had. 
In Chapter II, phylogeny was defined as the development of man 
from the lowest cell to the species; ontogeny, the development of man from 
the primitive cell to the grown up individual. Arrests, hence, occur in both 
phylogeny and ontogeny. 

Arrests in Phylogeny are a condition which exists in an organ or 
structure resembling vertebrate forms, namely fish, reptile, bird and 
mammal and hence called reversions. 

Arrests in Ontogeny are a condition which exists in an organ or 
structure that has not attained the full development of the human type. 
This is excellently illustrated in the following diagram (Fig. 52). Man, 

MAN 

/ \ 6™ PERIOD OF 5TRE55 
MAMMAL5 / \ (AROUND 60 YEARS) 

/ \ %\5™ PERIOD OF STRESS 
EGG-LAYING /$ \ O MAROUND 45 YEARS) 
MAMMALS/^ \ %\ 4 ™ PERIOD OF STRESS 

/cK., \ a\( I4 TH TO 25™ YEAR) 

SAimnDSinAF /^ ^ \9A 3 RD PERIOD OF STRESS 

OAUKUHSIUAL / kj ^ \ -t\ ffiw ta i ? tm Y FARl 

(BIRDS & REPTILES^ '^ N %X ] 

f-&~~. ^ ^\2 N0 PERIOD OF STRESS 

/S ""---.. ^.\MFR0M BIRTH TO 5 RD YEAR) 

ICHTHY0P5IDAE / Q ""----. ^^\\ I st PERIOD OF STRESS 
(FISH & FR0G5) / l;::. : :-ik (DEVELOPMENT IN UTERO) 

primitive cell (the amoeba)/ \primitive clll (the ovum) 

race development individual development 

Diagram Showing Developmental Stages of Man 

Figure 52 
Diagram showing developmental stages of man (original). Man, in his phylogeny (evolu- 
tion) from the amoeba passes through all the stages of development from fish to reptile 
and from bird to mammal, arriving at the highest development or human being. In 
his ontogeny or individual development from the primitive cell passes through different 
periods of stress. It is at these periods of stress that new structures develop and others 
disappear under the law of economy of growth. These periods of stress are critical 
moments in the life of the individual. 

97 



98 DEVELOPMENTAL PATHOLOGY 

at the first period of stress in his development (phylogeny) in utero, passes 
through the various stages of fish, reptile, bird and mammal. 

Owing to an unstable nervous system in the parents, arrests may take 
place at any one or a number of these types so that when the child is born, 
his general appearance or a structure or organ may resemble one or more 
of these vertebrate forms. Again, man in his development from the 
primitive cell (ontogeny) passes through different periods of stress at 
which time a new function disturbs the physiologic balance previously 
existing. At these periods, the organism must adapt itself to the disturb- 
ance. Owing to an unstable nervous system in the child, excess or under 
development may and often does take place at these periods. Race 
development (phylogeny) shows retrogressive changes, while individual 
development (ontogeny) shows individual arrests. Occasionally, the 
disturbance is so great that the child does not survive. Again the child 
may retain reserve forces or human skill may bridge over these periods and 
the individual may succumb later, as a result of the new functional disturb- 
ance. 

The nervous system is composed of two factors, one of which is to 
give action, the other to check excessive action. An unstable nervous 
system is one in which the check on excessive action has either not been 
properly developed or has been weakened. 

The important factor regulating bodily nutrition is the nervous 
system. All parts of the body contain nervous tissues which influence 
each other by impulses passing over nerve fiber. In the lowest organisms 
these nervous influences are indeterminate, irregular. They exist in 
tissues and organisms in which, as at certain phases of fetal life, nerves of 
definite structure cannot be determined. That nervous influence, or in 
other words, impulses transmitted from one cell to another, occur in 
tissues where the histologic structure of nerves cannot be demonstrated, 
is evident in the fact that the mammalian heart beats automatically before 
nerves are demonstrable in it, performing acts similar to those which are 
regulated by nerves. 

Inhibition. In higher animals, nervous impulses are inhibited, 
controlled and originated by the higher nerve centers. The highest 
functions of the nervous system are centered in the brain. The power of the 
nerves over nutrition is more strikingly shown in the nerves which control 
the nutritive supply of the muscles. If the trunk of a motor nerve be cut, 
the nerve fibers below the severed point, and the muscles supplied by the 
nerve, degenerate and atrophy. This also occurs if the nerve be com- 
pressed, inflamed, or if the ganglion cells in the spinal cord, from which 
the nerve fibers spring, are destroyed by injury or disease. If the nerve 
trunk be cut, the degenerated fibers are at length replaced in the process 



A STUDY IN DEGENERATIVE EVOLUTION 99 

of healing by new fibers and the muscle recovers its function and nourish- 
ment when the regenerated fibers grow out to it. If the nerve be com- 
pressed or inflamed a similar process occurs. Regeneration takes place 
from the central end and nutrition of the atrophied muscles is restored. 
But if the ganglion cells have been destroyed, the atrophy and loss of 
functions in the muscle is permanent. To this there is one exception. 
It is possible by the operation of nerve grafting to bring degenerated nerve 
and muscle fibers under the influence of nerve fibers still in connection 
with live ganglion cells, and under the influence of these cells they may be 
regenerated. 

An unstable nervous system in the parents causes nutritive disturbances 
in the fetus at the first period of intrauterine stress. The brain is one of 
the fetal structures frequently involved, and, since the brain of the child 
presides over the child 's development, an unstable brain produces nutritive 
disturbances. Thus, there results a vicious circle which calls for serious 
consideration. How far a defectively developed hypophysis may influence 
ossification of tissue in different parts of the body is yet to be determined. 
There is no doubt that from what little we know about its influence upon 
other tissue development, it must exert an influence on bone tissue. 

When defects in brain structure occur, the different forms of degeneracy, 
already mentioned in Chapter III, appear. Degenerates possess a greater 
number, and, as a rule, more marked forms of stigmata than normal 
individuals. Therefore it is best to consider the nutritive disturbances 
of the brain of degenerates before discussing the effects of an unstable 
nervous system upon the development and growth of other structures of 
the body. 

Brain Degeneracy. Of the check on excessive action due to a want 




Figure 53 

Durencephalous child (original). Marked arrest of development of the brain, cranium and 

ear. An arrest in phylogeny at the reptilian stage. 



100 DEVELOPMENTAL PATHOLOGY 

of proper development, the most extreme illustration is that of the duren- 
cephalous child (Fig. 53), which so often appears in degenerate families. 
Here the cerebral hemispheres, and in fact everything but the medulla and 
pons, may be absent. In this illustration is shown the arrest of develop- 
ment of the skull at the prevertebrate period. Here the secondary skull, 
formed by the dermal bones, which is an advance in evolution, is lacking. 

Starting with such an extreme expression of brain degeneracy, a wide 
but closely linked range of deficiencies may be found in degenerates involv- 
ing, even in some seemingly normal individuals, more than simple deficiency. 
What was pointed out by E. C. Spitzka, of New York, thirty years ago, 
concerning the brain of hereditary lunatics, is equally true of the brains 
of other degenerate branches of the same tree. The conventional idea, 
associating idiocy and imbecility with quantitative deficiency of the fore- 
brain only, is, as Spitzka remarks, a very imperfect one. The researches 
of numerous observers have shown that qualitative defects (using the term 
"qualitative" in its wider sense to cover both morphologic and histologic 
aberrations) are as common, and are more characteristic features of the 
degenerate brain. 

Classification of Brain Defects. These defects occur under the 
following heads: 1. Atypical asymmetry of the cerebral hemispheres as 
regards bulk. 2. Atypical asymmetry in the gyral development. 3. 
Persistence of embryonic features in the gyral arrangement. 4. Defective 
development of the great interhemispherical commissure. 5. Irregular 
and defective development of the great ganglia and of the conducting 
tracts. 6. Anomalies in the development of the minute elements or 
neurons (as the cells and associating of fibers are now generally called) of 
the brain. 7. Abnormal arrangements of the cerebral vascular channels. 

All these conditions, separately or in varying degree of combination, 
are occasionally found in the brain of paranoiacs, moral imbeciles, criminals, 
deaf-mutes, congenital blind, idiots, paupers, harlots, extreme egotists, 
one-sided geniuses, kleptomaniacs, habitual liars, "smart" business men 




Figure 54 
Fetal brain at six months (Bastian). This brain is without convolutions; should arrests take 
place at this period the child when born would rank below the lemurian type in phyto- 
geny. 



A STUDY IN DEGENERATIVE EVOLUTION 



101 



and "eccentric" people. These display stigmata to a marked degree. 
Before considering the different types of defective brains already enumerat- 
ed, two extremes of normal healthy brains need comparison. Fig. 54 
illustrates a fetal brain at six months. No convolutions have yet developed, 
though the fissure of Sylvius is well marked. The surface of the brain is 
smooth and, therefore, is below the lemur type of development. Comparing 
this brain with that of Fig. 55 it will be noticed that, from an atavistic 




Figure 55 
Normal healthy brain (Carus's "Soul of Man"). This is a normal healthy brain. 

point of view (where no convolutions are present), it represents the verte- 
brate types below the lemurs in intelligence. The contrast between this 
fetal brain and that of the ideally normal, highly developed one of the 
great mathematician, Gauss (Fig. 56), indicates a long step in phylo- 




Figure 56 
Brain of the mathematician Gauss (Vogt). This brain shows a much higher development 
than the previous illustration. The convolutions are smaller, giving a wider surface to 
the gray matter. 



102 DEVELOPMENTAL PATHOLOGY 

genetic and ontogenetic development. Deficiencies in brain development, 
therefore, starting with the six months ' fetal brain, may take any one of 
the various forms before the type development is attained. 

Types of Brain Arrest. Illustration of different types of brain 
arrest enumerated by Spitzka is first seen in Fig. 57, which shows asym- 




FlGUKE 57 

Paranoiac criminal brain (Ziegler). The left cerebral hemisphere is markedly arrested in 
ontogenic development. The convolutions are small to compensate for bulk. 

metry of the cerebral hemispheres as regards bulk. This brain, observed 
by J. G. Kiernan, came from a paranoiac criminal who died in the Chicago 
(Cook County) Hospital for the Insane. 

A very similar brain was also observed by Kiernan in one of the 
paranoiacs dying in the New York Insane Hospital. Similar brains have 
been observed in deaf-mutes, whose mental states passed muster because 
of the allowance made for mental deficiency due to deaf muteness. A 
brain showing asymmetry was found in a French physician of standing, 
who was a member of a mutual autopsy society. He proved, however, 
to have had degenerates in his ancestry and exhibited peculiarities which 
showed that much degeneracy, due to ancestry , had been corrected by proper 
training. The defects enumerated under Spitzka 's second head are like- 
wise observable in the illustration given. The gyres are not only asym- 
metrical as to their number in the two hemispheres, but also as to their 
size. 

Fig. 58 well illustrates the third classification, in which the presence 
of embryonic, as well as atavistic features, in the gyral arrangement, and 
the brain as a whole, are concerned. This is the brain of an idiot (Fig. 104). 
The arrest of development took place at the lemurian period and compares 
favorably with Fig. 20. The anterior and posterior development of the 
cerebrum is wanting and the gyral arrangement and size are embryonic. 
Another illustration of the third classification, that of an imbecile (Fig. 59), 
examined by E. C. Spitzka shows an arrest of fetal development at a higher 



A STUDY IX DEGENERATIVE EVOLUTION 103 

phylogenetic period than that of Fig. 58. The anterior and posterior 
development cover both the cerebellum and the optic lobes which was not 
the case in Fig. 58. In this illustration, the convolutions, in general, were 




Figure 58 
Brain of an idiot (Ziegler). This brain became arrested in development in its phylogeny at 

the lemurian stage. 

few, large and well marked. The occipital and parietal lobes preponderated 
in mass, as compared with the temporal and frontal. The latter were 
greatly hollowed out on the orbital face, and the gyri here found were few, 
simple and atypical. On the whole, the convolutions of the right hemi- 
sphere were better marked and the secondary folds more numerous than 
those of the left hemisphere, and the type of the convolutions presented 




Figure 59 

Brain of an imbecile (Spitzka). The convolutions are few, large and well marked. The 

arrest in phylogeny has taken place a little later than the previous illustration. 

differences on the two sides. The most pronounced differences were 
exhibited in the island of Reil and in the occipital lobe. The island of 
Reil on the left side had fewer and flatter gyri than that of the right side, 
and resembled in its general aspect the first impression of the brain of an 
orang-outang. The right island had six folds better marked than those 
of the left side, but their type was decidedly radiatory, which was in relation 
with the unusual shortening of the insular field. The external perpendicu- 
lar occipital sulcus (which Bischoff never found in the adult human brain, 
but which has been found persistent in a case of imbecility with moral 
perversion by Sander, and in a sane neurotic individual by Meynert) was 
finely marked upon the right side of the brain under consideration. The 



104 



DEVELOPMENTAL PATHOLOGY 



fissure was very deep; its posterior wall was slightly bevelled and covered 
several secondary gyri of its anterior walls. It differed in position from 
the similar fissures described by Meynert and Sander in that it did not, as 
in their cases, unite with the internal perpendicular occipital sulcus and 
thus simulate the specialized arrangement found in the anthropoid apes. 
It was merely the unobliterated external occipital fissure of the embryo, 
and, as in the latter, its medial end, if prolonged, would have fallen behind 
the internal perpendicular occipital sulcus. The anomaly consisted, 
therefore, in the preservation of an embryonic feature. 

The fourth classification, defective development of the great inter- 
hemispherical commissure, is one of great importance. The corpus 
callosum, which unites the two hemispheres of the brain, is a broad thick 
mass of fibers which pass transversely across the median plain. These 
fibers radiate in all directions towards the cortex and intersect the fibers 
of the corona radiata. Defect, then, in the development of the corpus 
callosum (which frequently occurs in degenerates) must necessarily affect, 
to a greater or less extent, the mentality of the individual. It will be seen 
that mentality is not dependent on the relative proportions of white and 
gray matter so much as upon the great bundles of fibers, known as the 
corpus callosum which connect the two sides of the brain. 

In the fifth classification, irregular and defective development of the 
great ganglia and of the conducting tracts involves many strictures. 
Nay, part of the brain may cease to develop or become diseased, and 
deficiency in cell area, fibers extending from those cells through the ganglia 
or the ganglia themselves may be undeveloped. 




Figure 60 
A diagrammatic scheme of the course of the fibers within the brain (Ramon y Cajal) . A, 
corpus callosum; B, anterior commissure; C, pyramidal tract; a, neuron with projective 
fibers and collateral commissural fibers; b, neuron with fibers to the corpus callosum; 
c, neuron with associative fibers; ed, terminal ramifications of various neurons in the 
cerebral cortex. 



A STUDY IN DEGENERATIVE EVOLUTION 105 

These nerve fibers connect with every tissue of the body. Were it 
not for the manifold connections of the nerve cells in the outer layers of 
brain matter with each other as well as with the rest of the body by means 
of the millions and millions of fibers which make up the white matter such 
a brain would be as useless as a multitude of telephone or telegraph stations 
with all interconnecting wires destroyed. Fig. 60 shows some of these 
fibers extending from the cortical surface through the great ganglia down 
the spinal cord which connect every structure of the body below the head 
with the brain. 

Cerebral Localization. From the sequelae of injuries, including 
gun shot wounds, surgeons have been able to outline the different areas 
of the brain. This has been accomplished by examination of the body 
when brain lesions have occurred and noting the structures involved. 
These observations have, from time to time, been recorded, as a result 
of which a map has been produced, Fig. 61, giving an outline of the brain 



Figure 61 
Brain map; specialized function in the cortex cerebri (Dana). From gun shot wounds and 
other injuries of the brain and their results upon the different tissues of the body, sur- 
geons have been able to map out the areas of the brain affecting nutrition. 

areas in direct communication through the nerve fibers with different 
parts of the body. Areas of the brain which preside over the action of 
the various structures of the body may be improperly developed, with 
the same result as disease of the same areas only here the check influence 
on development is lacking. 

If a section of the brain is prepared at any locality mapped out in 
Fig. 61, nerve cells in different shapes and degree of development will be 
observed as seen in Fig. 62. These nerve cells and their associating fibers 
are the structures included in Spitzka 's six classifications. These cells or 
neurons, through their prolongations, establish relations with other neurons, 
and these are grouped into the larger and smaller nerve trunks which 
connect the different parts of the brain or extend through the spinal tract 
to all parts of the body. 



106 



DEVELOPMENTAL PATHOLOGY 



In the seventh classification, deficiencies in the cerebral vascular 
system underlie the pathologic phenomena the basis of infantile cerebral 
paralysis and allied hereditary and congenital states. The degenerate 
conditions in the spinal cord are essentially those described by Spitzka as 




Figure 62 

Cortical specialized cells of the brain (Dana). These cells are in different stages of phylo- 

genic development, some with their connecting fibers. 

occurring in the brain. Similar vascular states, either as to irregularities 
in the number of vessels or in the vessels themselves, underlie hereditary 
ataxias and other congenital and hereditary spinal cord disorders. 

Influence of Nerves on Nutrition. The general nutrition of the 
body is evidently under the influence of the nervous system. According 
to DeMoor, the causes which are active in producing degeneration may 
all be referred to the limited nature of the means of subsistence, that is 
to say, of nourishment of the body tissues. This limitation causes a 
struggle between organisms and between their component parts. In the 
course of the perpetual struggle for existence among the different parts 
of an individual, the organs which have ceased to be functional tend to 
disappear, their nourishment being absorbed by the active parts. 

The stature is determined in some unknown way by the action of 
organs closely connected with the brain. The thyroid gland through its 
peculiar connection with the nervous system exerts an influence shown 
in goiter, myxedema and Grave's disease (exophthalmic goiter). The 
influence of the thyroid on growth is shown in the effects of feeding thyroid 



A STUDY IN DEGENERATIVE EVOLUTION 107 

gland to cretins (dwarf idiots whose thyroids are undeveloped or degenerat- 
ed). Such dwarfs usually begin to grow as soon as the thyroid substance 
is fed to them. We may best explain its action through the nervous 
system. The limitation of growth is probably due to the action of another 
gland, the pituitary body or hypophysis, in close connection with the 
brain. When this organ is diseased, abnormal growth takes place, some- 
times in the form of an enlargement of the extremities (acromegaly), 
sometimes in the. growth of the whole body by which the person becomes 
a giant or is arrested in development. The hypophysis, therefore, regulates 
growth of the body. 

Of the various causes which produce defects in body development, 
imperfect developed brain areas, want of cell development and con- 
necting nerve fibers with different parts of the body, are underlying factors. 

Summary 

It is necessary to have a clear understanding of the law upon which 
arrest and excessive growth is dependent. 

Phylogeny is the development of man from the lowest cell to the 
species. Ontogeny is the development of man from the primitive cell to 
the fully grown individual type. Arrests occur in both. 

Arrests in phylogenetic development resemble fish, reptile, bird and 
mammal types and are hence atavistic. 

Arrests in ontogenetic development exist in organs or structures that 
have not attained the full human type. 

A diagrammatic figure aptly illustrates man's development from the 
first period of stress through fish, reptile, bird and mammal types of intra- 
uterine life. 

An unstable nervous system in the parents cause these arrests in the 
child to take place at any of the intrauterine periods of stress. In man's 
ontogenetic development, in passing through the different periods of 
stress, his physiologic balance may be so disturbed by new functions that 
he cannot survive. Sometimes the child may be able to overcome these 
for a time but finally succumbs as result of the disturbance. 

The function of the nervous system is to give and check excessive 
action and to regulate bodily nutrition. An unstable nervous system is 
one not properly developed or weakened. 

Nervous influences in the lower organisms are indeterminate and 
irregular; in the higher animals, they are dependent upon higher nerve 
centers. 

Unstable nervous systems of parents cause fetal nutritive disturbances 
oftentimes involving the brain. 



108 DEVELOPMENTAL PATHOLOGY 

Durencephaly is frequent in degeneracy, sometimes only the medulla 
and pons are present. 

Spitzka has shown the relation between the brains of the hereditary 
insane and other degenerate conditions. The author has taken Spitzka 's 
seven classifications as his guide in the study of brain defect. 

The thyroid gland has a peculiar influence on growth, through the 
nervous system. The pituitary gland also exerts an influence on growth. 
Disease of this organ results either in dwarfism or giantism. 



Chapter X 

AN UNSTABLE NERVOUS SYSTEM THE CAUSE OF NUTRITIVE 

DISTURBANCES 

Checks on Excessive Action Weakened 

(1). Relaxations of Checks on Excessive Action. These are 
due in the order of their severity to excesses of all kinds, to toxic agents, 
contagious and infectious diseases, heredity, consanguinous and ueurotic 
inter-marriage, school strain and neurasthenia from any cause in both 
parent and child. 

(2). Agencies Which Produce Neurasthenia or Fagged-out 
Nervous Systems. These are divisible into the following groups; those 
embracing condiments, medicines, foods and beverages; those arising from 
occupations and excessive indulgence, and those from resultant worries 
and uncertainties. 

Tobacco is the most common causative factor, while alcohol and 
opium contend for second place both as to use and deleterious effects. 
Alcohol has been repeatedly charged with being the greatest factor in 
degeneracy. The influence of alcohol on the individual must first be studied 
to determine its potency and method of action as a cause of race deteriora- 
tion. Careful medical researches have shown that alcohol produces a 
nervous state closely resembling that induced by the contagions and 
infections, and often accompanied by mental disturbance. The acute 
nervous state to which the term "alcoholism" was applied by Magnus 
Huss has all the essential characteristics of the nervous state due to the 
contagions and infections, that is mental exhaustion. The action of 
alcohol may be limited to the central nervous system and thus produce 
hereditary loss of power. It may cause changes or degeneracies in the 
peripheral nerves, which in the off-spring find expression in spinal cord 
and brain disorder through extension of the morbid process. But for its 
deteriorating effects on the ovaries and testicles, alcohol would be a most 
serious social danger. Through these, however, it tends to prevent the 
survival of the unfit rather than to develop degeneracy. 

Opium seems to be the Charybdis on which the human bark strikes 
that has escaped from the Scylla of alcohol. Its abuse as a narcotic is 
much older than is generally suspected even among the English-speaking 
races. Murrell, over ten years ago, demonstrated that the inhabitants of 
the Lincolnshire fens had long employed opium as a prophylactic against 
malaria. The ratio of insanity in these regions proved to be very great. 
The same conditions obtained in certain malarial regions of New Jersey 

109 



110 DEVELOPMENTAL PATHOLOGY 

and Pennsylvania, where the use of strong infusions of the poppy was 
common. The statistics of Rush as to opium-caused insanity in Pennsyl- 
vania indicate that the percentage of American opium abuse at the begin- 
ning of the nineteenth century was marked. The drug differs in two 
important aspects from alcohol — it is nearer in chemical composition to 
nerve tissue, and the tendency to its use may be transmitted by the mother 
directly to the fetus, since it passes through the placenta very often un- 
altered. 

Opium is a more dangerous factor of degeneracy than alcohol, since 
the opium habitue must be in a continuous state of intoxication to carry 
on his usual avocation, while abstinence from alcohol is perfectly compatible 
with proper work on the part of the alcoholist. The opium habit is 
increased by the propaganda carried on by its habitues, who justify their 
position by urging the use of opium for any ailment, however trifling. 
Opium, like alcohol, causes nervous exhaustion similar to, but greater 
than, that of the contagions and infections. The affinity of opium to 
nerve tissue; its stimulation of the heart, causing increased blood supply 
to the brain; from its action on the bowels and the resulting increased 
work of the liver; all serve to intensify this nervous state. Opium does 
not interfere with the structure and fecundation of the ovaries and testicles 
like alcohol, hence the danger of the opium habitue's children surviving. 
Opium, when smoked, stimulates the reproductive apparatus and thus 
greatly increases the number of degenerates due to this habit, although 
the defects due to the inheritance of the habit and their consequences 
lessen survivals. 

With tobacco, as with alcohol and opium, the statistic method generally 
proves fallacious when applied to degenerative effects. The most careful 
researches show that the typical effects occur as a rule after long continued 
use of tobacco, sometimes not until twenty years or more. While many 
smokers reach old age, many fail to do so because they are smokers. The 
skin is subject to itching and reddening; the nerves of taste are blunted 
and patches develop in the throat; loss of appetite, epigastric fulness, 
pain, vomiting and disturbance of bowel function are common. Menstrual 
disturbance occurs in women and in female cigar-makers abortion and 
pluriparity are frequent. The sexual appetite is impaired and sometimes 
sterility and impotence occur. Disturbed heart action, palpitation, rapid 
and intermitting pulse, precordial anxiety, weakness, faintness and collapse, 
with sclerosis of the coronary arteries of the heart and left ventricular 
hypertrophy occur often. Cigars and cigarettes produce irritation of the 
nose and mucous membrane, diminished smell, chronic hyperemia of the 
epiglottis and larynx, and sometimes of the trachea and bronchi, predis- 
posing to tubercular infection. Nicotine amblyopia is common, with 






A STUDY IN DEGENERATIVE EVOLUTION 111 

central disturbances of the field of vision and slight color blindness. Often 
there is disorder of the ear tubes and congestion of the drum with loss 
of auditory power and consequent noises in the ear. The central nervous 
system is affected. In high schools non-smokers progress faster than 
smokers. Child smokers from nine to fifteen years of age exhibit less 
intelligence and more laziness or other degenerative tendencies. Adults 
have head pressure, sleeplessness or drowsy stupor, depression, apathy 
and dizziness. There may also be ataxic symptoms, paretic weakness of 
bowels and bladder, trembling and spasms. Tobacco insanities, though 
comparatively rare in smokers, are common in snuffers and still more so 
in chewers. In the precursory stage, which lasts three months, there are 
general uneasiness, restlessness, anxiety, sleeplessness and mental depres- 
sion, often of a religious type. After this occurs precordial anxiety, and 
finally the psychosis proper, consisting of three stages: 1. Hallucinations 
of all the senses, suicidal tendencies, depression, attacks of fright, with 
tendency to violence and insomnia. 2. Exhilaration, slight emotional 
exaltation, with agreeable hallucination after from two to four weeks' 
relaxation, again followed by excitement. 3. The intervals between 
exaltation and depression diminish and the patient becomes irritable, but 
otherwise not alive to his surroundings. Perception and attention are 
lessened. The patient may be cured in five or six months if he stop tobacco 
during the first stage. In a year or so, he may recover during the second 
stage. After the third stage, he is frequently incurable. As the patient 
often becomes (especially by the use of the cigarette) an habitue before 
puberty, the proper development and balance of the sexual and intellectual 
system is checked. These patients break down mentally and physically 
between fourteen and twenty-five. The moral delinquencies, other than 
sexual, are often an especial tendency to forgery and deceit of parents. 
Frequently, adolescent insanity (hebephrenia) is precipitated by tobacco. 
The cigarette, if used moderately, may be a sedative, but as used is a 
stimulant, and is often made of spoiled tobacco, resembling in re-action 
morphine, and acting on animals in a somewhat similar manner. As 
tobacco turns the salivary glands into excretory glands, it leads to imper- 
fect digestion of starch and to consequent irregular fermentation in the 
bowels, thus at once furnishing a culture medium for microbes, from which 
to form more violent toxins, and likewise creating leucomaines, to damage 
a nervous system over-stimulated by nicotine. This is one great reason 
why those who use snuff and chew tobacco become insane more frequently 
than smokers, albeit these last are not exempt. 

Statistics from the female employes of the Spanish, French, Cuban 
and American tobacco factories, while defective and somewhat vitiated 
by the co-existence of other conditions producing degeneracy, support 



112 DEVELOPMENTAL PATHOLOGY 

the opinion that the maternal tobacco habit (whether intentional or the 
result of an atmosphere consequent on occupation) is the cause of fre- 
quent miscarriage, of high infantile mortality, of defective children and 
of infantile convulsions. Tobacco, therefore, in its influence on the pater- 
nal and maternal organism, exhausts the nervous system so as to produce 
an acquired transmissible neurosis. 

Tea. Professional tea tasters have long been known to suffer from 
nervous symptoms. Very early in the practice of their occupation the 
head-pressure symptoms of neurasthenia appear. Tremor also occurs 
early. While changes in the optic nerve have not been demonstrated 
beyond a doubt, still eye disorders have been observed in the pauper tea 
drinkers of the United States and in the tea tasters of Russia, indicating- 
similar changes to those produced by tobacco and alcohol. The tea- 
cigarette habit has these effects. Bullard finds that tea has a cumulative 
effect. In his experience toxic effects are not produced by less than five 
cups daily. The symptoms manifested are those of nervous excitement 
resembling hysteria, at times almost amounting to fury; nervous dyspepsia; 
rapid irregular heart action; heart neuralgia: helmet-like sensation and 
tenderness along the spine. James Wood, of Brooklyn, found that ten 
per cent, of those under treatment at the city hospitals exhibited similar 
symptoms. Of these, sixty-nine per cent, were females, and every symptom 
ascribed by Bullard to tea was seen by Wood in his cases, who also found 
that the women manifested irregularities in menstruation of neurasthenic 
or hysterical type. He found that these symptoms were produced by 
one-half of the quantity of tea charged with these effects by Bullard. 
The Lancet several years ago, from an editorial analysis of the effects of 
tea-tippling, took the position that in no small degree nervous symptoms 
occurring in children during infancy were due to the practice of the mothers 
both of the working and society class indulging in the excessive use of tea, 
the excess being judged by its effects on the individual and not by the 
amount taken. Convulsions and resultant infantile paralysis were fre- 
quently noticed among the children of these tea-tipplers. Observations 
among the factory population and the workers in the clothing sweat-shops 
show that tea neurasthenia, presenting all the ordinary symptoms of 
nervous exhaustion, is especially common. It is evident that tea produces 
a grave form of neurasthenia readily transmissible to descendants. In 
addition to its effects directly upon the nervous system, tea tends to check 
both stomach and bowel digestion, and this increases the self-poisoning 
which is so prominent a cause, consequence and aggravation of these 
nervous conditions. 

Coffee exerts an action very similar to that of tea, although the 
nervous symptoms produced by it are usually secondary to the disturbances 



A STUDY IN DEGENERATIVE EVOLUTION 113 

of the stomach and bowel digestion. Coffee produces tremor, especially 
of the hands, insomnia, nervous dyspepsia and helmet sensations. With 
the exception of certain districts of the United States coffee abuse is not 
carried to such an extent as tea, albeit in these, as in some portions of 
Germany, the habit is an excessive one. The conditions described result 
in Germany as frequently as they do in the United States. Mendel finds 
that in Germany coffee inebriety is increasing and supplanting alcohol. 
Profound depression with sleeplessness and frequent cortex headaches are 
early symptoms. Strong coffee will remove these temporarily, but it 
soon loses its effect and they recur. The heart's action is rapid and 
irregular and nervous dyspepsia is frequent. L. Bremer, of St. Louis, has 
observed similar conditions among both Germans and Americans there. 

Coca. While coca took its place but recently among the toxic causes 
of modern degeneracy, it was a factor of Peruvian degeneration long ere 
the discovery of America. Forty-three years ago, Europeans or people 
of European origin in different parts of Peru had fallen into the coca abuse. 
A confirmed chewer of coca, called a coquero, becomes more thoroughly a 
slave to the leaf than the inveterate drunkard is to alcohol. Sometimes, 
the coquero is overtaken by an irresistible craving and betakes himself for 
days together to the woods and there indulges unrestrainedly in coca. 
Young men of the best families of Peru are considered incurable when 
addicted to this extreme degree, and they abandon white society and live 
in the woods or in Indian villages. In Peru the term "white coquero" 
is used in the same sense as irreclaimable drunkard. The inveterate 
coquero has an unsteady gait, yellow skin, quivering lips, hesitant speech 
and general apathy. The drug has assumed prominence in the field of 
degeneracy, since the discovery of its alkaloid, cocaine. In both Europe 
and the English-speaking countries, the world over a habit has resulted 
which, while much over-estimated, is undoubtedly growing and aggravating 
as well as producing degeneracy. Many of the cases reported as due to 
cocaine are, however, chargeable to the craving of the hysteric or neuras- 
thenic to secure a new sensation or the desire on the part of the opium or 
whiskey fiend to try a dodge for forgiveness by friends. The habit is very 
frequently induced by patent medicines taken to cure catarrh by the 
neurasthenic or to cure nervousness by hysterics as well. As deformities 
of the nose passages predispose to "catarrh," patent medicines for local 
application containing cocaine are frequently employed in the treatment 
of this supposed constitutional disease, with the result of aggravating the 
original degeneracy. The youth under stress of puberty frequently 
ascribes all his ills to catarrh and for it often employs snuffs containing 
cocaine, and his nervous condition is much aggravated thereby. Among 
the nostrums urged in the newspapers and magazines for this condition 



114 DEVELOPMENTAL PATHOLOGY 

so often resultant on nerve stress alone is a snuff containing three per 
cent, of cocaine. From the description given by Johnson of the coquero 
there can be no doubt that tramps, errabund lunatics and paupers result 
from this habit to give birth to degenerates in the next generation. 

Lead produces in those exposed to its fumes a systemic nervous 
exhaustion, characterized by local paralysis about the wrist, as well as the 
general symptoms of profound systemic nerve tire. This may result, as was 
pointed out nearly half a century ago in acute insanity of the confusional 
type followed very often by mental disorder of a chronic type resembling 
paretic dementia. In some cases, the patient recovers from the acute 
insanity to suffer thereafter from epilepsy. In other cases, an irritable 
suspicional condition also results, in which the patient may live for years, 
marry and leave offspring. This last condition and the epileptic are the 
most dangerous as to the production of degeneracy. The women employed 
in the pottery factories in Germany suffer, according to Rennert, from a 
form of lead poisoning which produces decidedly degenerative effects upon 
the offspring. These women have frequent abortions, often produce 
deaf-mutes and very frequently macrocephalic children. 

Brass workers suffer from a nervous condition very similar to that 
produced by lead. Hogden, of Birmingham, and Moyer, of Chicago, have 
called attention to the grave forms of nervous exhaustion produced among 
brass workers. The period during which the patient is able to pursue the 
occupation without breaking down is longer than that of lead workers. 
Women, like men, are exposed to this condition. The chief effects pro- 
duced, so far as the offspring have been observed, are frequent abortions 
and infantile paralysis. 

Mercury. The occupations involving exposure to mercury, whether 
mining, mirror-making or gilding, produce forms of systemic nervous 
exhaustion in which the most marked symptom (but less important from 
a sanitary standpoint) is a tremor amounting at times almost to the shaking 
palsy. Like all other systemic nervous exhaustions, the mercurial one 
may appear as degeneracy in the offspring. The employment of women 
in match factories and tenement-house sweat-shops is growing. The 
chief toxic effect of phosphorus is not the localized jaw necrosis. This is 
but an evidence of the progressive saturation of the system with phosphorus, 
and bears the same relation to the more dangerous effects of phosphorus 
that "blue gum" does to the systemic effects of lead. 

Every condition of toxic origin capable of producing profound systemic 
nervous exhaustion in the ancestor, and especially in the ancestress, may 
produce degeneracy in the descendant. With the growing tendency of woman 
to pass from the ill-paid work of the seamstress to the better paid but 
dangerous occupations, a certain seeming increase in degeneracy must result. 



A STUDY IN DEGENERATIVE EVOLUTION 115 

Toxins. The influence of contagious and infectious diseases upon 
developmental pathology or suppressive evolution is by no means slight. 
Any disease that produces grave constitutional defects in the parent is 
likely to be intensified in the offspring. The greatest social dangers result 
from tuberculosis; the next from syphilis. Typhoid fever, scarlatina, 
small-pox, measles, diphtheria, whooping-cough, and all contagions, 
however, may produce these constitutional defects, either through the 
pregnant mother or through their secondary effects on the ancestor's 
constitution. If the subject be attacked before the close of the periods 
of dental stress, an arrest of development of the bones of the face may 
result, with irregularities in the shape and the position of the teeth. These 
then are stigmata of degeneracy especially due, in the individual presenting 
them, to the contagions and infections rather than to inheritance alone. 

Two agencies producing profound constitutional alteration in a victim, 
which predispose to degenerative factors like alcohol and which increase 
the effect of these are, as Kiernan pointed out nearly a quarter of a century 
ago, traumatism and isolation. There is a deep-seated neurosis produced 
by these, attended by a suspicional state, and accompanied by metabolic 
changes which result in glycosuria, and which aggravate the co-existent 
neuroses. The influence of these states on the offspring I have elsewhere 
pointed out in their relation to the effect of alcohol. 

The relations of heredity are far more intricate than is usually assumed 
to be the case in the average discussion of the subject. The problem 
consequent on impregnation involves more than the mere carrying of the 
mixture of parents in a fully developed form through intrauterine life. 
Impregnation, moreover, itself depends on the preparation of the ovum 
for the spermatozoon. The centrosome (a body belonging to the period 
when the ovum has passed from the parthenogenetic to the primitive 
hermaphroditic stage) has to disappear ere its quasi-function is assumed 
by the spermatozoon. Futhermore when the germinal streak has occurred 
this must be preserved from duplication tending to make duplications of 
cells or organisms or other minor manifestations of the conditions resultant 
in double monsters. 

As all vertebrate organs pass through the same stages before definitely 
differentiating, the later types have to gain at the expense of the earlier 
and hence must receive greater impetus from the direct ancestors. The 
want of this impetus is shown in the various defects and departures from 
type which occur in the different degeneracies and congenital defects. 
For this reason, the descendants of a victim of morbidity or abnormality 
do not always exhibit the disorders, or not to the same degree. Sometimes 
the superior strength of the maternal ancestor and her consequent power 
of nourishment carry the fetus through the period of defect shown by the 



116 DEVELOPMENTAL PATHOLOGY 

father and consequently correct that defect. The types of heredity 
ordinarily considered are direct heredity where the individual takes after 
the immediate ancestry, and type heredity where he takes after the type 
to which he belongs. Concerned in this latter is atavism or reversional 
heredity, where the individual throws back to immediate remote ancestors. 
This element of atavism tends, by preserving the type, to offset the defects 
of immediate heredity and, indeed, often underlies the apparent differences 
between children of the same parents. It likewise prevents equal inherit- 
ance from both parents and sometimes favors inheritance of strength or 
defect from either. It underlies also so-called collateral or indirect heredity 
and the transmutation of heredity. While acquired defects and benefits 
may be, as even Weismann admits, inherited this can occur but rarely, 
since it not only implies weakness of atavism or type heredity, but likewise 
weakness of maternal constitution and environment during pregnancy 
and lactation. Much of the alleged inheritance of paternal defects is due 
to the environment of the mother produced by this defect, as I have else- 
where pointed out in the discussion of the influence of paternal alcoholism. 
What is true of alcoholism is, of course, true of all other degenerative 
factors. The neurasthenic influence of these on the maternal organism 
during pregnancy and lactation would through simple arrest of maternal 
function create defective offspring even were there no direct inheritance 
of defect. 

Morbid Heredity. Manifestations of morbid heredity may not be 
inheritance of the whole effect but disturbance of relations of structure 
and hence of function, producing a constitutional deficiency which takes 
the line of least resistance. The extent and direction of this line of least 
resistance depends upon the amount of healthy atavism which separate organs 
and structures of the body preserve. What is true of the organism as a whole 
is true of the cells forming its organs. While cell life is altruistic or subordin- 
ated to the life of the organ and through it to the life of the organism as a 
whole, still this altruism is not so complete as to entirely prevent a struggle 
for existence on the part of the cells or the individual organs. With advance 
in evolution, this struggle decreases to increase with the opposite procedure 
of degeneracy. Its action sometimes aids, and sometimes, when regular, 
prevents degeneracy. The vertebrate embryo of the higher type has in it 
all the potentialities for the organs and structures found in lower types. 
As ancestry is strengthened, these potentialities remain latent. In pro- 
portion as the ancestry becomes subject to nervous exhaustion these 
potentialities gain nutrition at the expense of the later acquired organs 
which are the ones likely to be affected by nervous exhaustion. Struggles 
for existence produce effects which are handed down by heredity or are 
fought by atavism. These two factors in heredity may play beneficial 



A STUDY IN DEGENERATIVE EVOLUTION 117 

as well as injurious parts on the offspring. As a rule, atavism plays a 
beneficial part in correcting degenerate tendencies. This part may either 
be complete in the shape of a perfect return to a normal ancestor or may 
be sufficient to moderate in the offspring the effect of an extended exhaus- 
tion of an immediate ancestor. 

Heredity is a prophecy of what may be, not a destiny which must be. 
Much is ascribed to heredity that is due to fetal periods of stress and mater- 
nal environment during ovulation and pregnancy. To the influence of 
such environment, is due the failure of the body plasm to reproduce acquired 
qualities. The germ plasm may, however, be affected by experiments 
suited to the fetal environment and periods of stress. Thus, also, are 
produced reversional tendencies through which the body plasm regains 
reproductive powers lost for the benefit of the whole organism. 

This principle is illustrated in the experiments of Dupuy. Here, 
while as a rule, the scions of guinea-pigs (rendered epileptic by section of 
the sciatic nerve) were epileptics and had deficient toes, still in some of 
them epilepsy resulted without the toe anomaly, and still more rarely the 
toe anomaly was present without the epilepsy. 

The same principle is shown by Charrin and Gley, who for five years 
conducted experiments calculated to throw light on the influence on the 
offspring of parental reception of virus. Either both male and female 
have been inoculated with the bacillus of blue pus or its toxins, or but one 
animal has been inoculated. The results have not been uniform. Most 
frequently there ensues sterility, abortion, or birth of progeny that die 
immediately. In rare instances, the offspring survive; more rarely still 
are they healthy. Certain rabbits (born of these undeveloped animals) 
were provided with enormous epiphyses (end of bones), the shafts of the 
bones being shortened. Two rabbits were born of a couple of whom the 
male alone received inoculations of sterilized culture. Five rabbits were 
born of these two, of which two were normal and a third (whose ears were 
rudimentary) died in a few days. In the remaining two the ears comprised 
only fragments with jagged upper edges. The tails were but two centi- 
meters long. The external orifice of the vagina (one rabbit was a male 
and the other a female) was oblique. One of the limbs (the hind in the 
male and the fore in the female) was much shorter than its fellow, showing 
a difference of four centimeters. The shortened limb ended in a kind of 
stump, there being no foot or toes. 

As Dareste has shown (and the fact has been corroborated by Spitzka) , 
embryologists can imitate natural malformation of the nerve centers by 
artificial methods. By wounding the embryonic and vascular areas of the 
chick's germ with a cataract needle, malformations are induced, varying 
in intensity and character with the earliness of the injury and its precise 



118 DEVELOPMENTAL PATHOLOGY 

extent. More delicate injuries produce less monstrous development. 
Partial varnishing or irregular heating of the eggshell, in particular, results 
in anomalies comparable to microcephaly (little head) and cerebral asym- 
metry. This latter fact (showing the constancy of the injurious effect of 
so apparently slight an impression as the partial varnishing of a structure 
not connected with the embryo at all directly) suggests the line of re- 
search to be followed in determining the source of the maternal and 
other impressions acting on the germ. What delicate problems are to 
be solved in this connection may be inferred from the fact that eggs sub- 
jected to the vibration and shocks of a railroad journey are checked in 
development for several days, or permanently arrested. A more delicate 
molecular shock during the maturation of the ovum, during its fertilization, 
or finally during embryonic stages of the more complex and therefore 
more readily disturbed and distorted human germ accounts for the disas- 
trous effect of insanity, emotion, or other mental or physical shock of the 
parent on the offspring. The cause of the majority of cerebral deformities 
exists in the germ prior to the appearance of the separate organs of the 
body. Artificial deformities produce analogous results because they 
imitate original germ defects, either by mechanical removal or by some 
other interference with a special part of the germ. Early involvement of 
the germ is shown by the fact that the somatic malformations of the heredi- 
tary forms of insanity often involve the body elsewhere than in the nervous 
axis. The stigmata of heredity — defective development of the uro-genital 
system, deformities of the face and skull, irregular development of the 
teeth, mis-shapen ears and limbs — owe their grave significance to this 
fact. Like deformities of the brain, these anomalies are also more marked 
and constant with the lower forms of the hereditarily based systematised 
perversions of the mind than the higher. It is easy from these results to 
understand how far and how deeply the nervous system has its part in 
the disorders of general development. It can be easily understood how 
the individuals who present most deformities are equally those who suffer 
from most decided disorders of the nervous system. 

In experimental teratology, the latest examples are the production of 
cyclopian monsters. Stockard by treating eggs of the common minnow 
(Fundulus) with solutions of magnesium chlorid immediately after fertiliza- 
tion has produced at will fifty per cent, of cyclopian monsters of various 
degrees of abnormality. Warren H. Lewis in a parallel series of experi- 
ments produced almost identical defects in this fish by destroying in later 
developmental stages the extreme anterior end of the medullary plate 
before it has invaginated to form the central nervous system. 

Consanguinous and Neurotic Marrjages are fruitful sources of 
degenerate children. Accentuation of family characteristics must always 



A STUDY IN DEGENERATIVE EVOLUTION 119 

happen from consanguinous marriages, for if there be taint in the family 
each member will have inherited more or less of it from the common ances- 
tor. 

Cousins, who are descendants of a common grandparent who was 
insane and of an insane stock inherit more or less of the insane diathesis. 
Even if the taint has been largely diluted in their case by the wise or 
fortunate marriages of blood-related parents, they have still inherited a 
neurotic tendency. If they marry they must not be surprised if that 
taint appears in aggravated form in their children. Children of such 
parents may be idiotic, epileptic, dumb, or lymphatic and the parents 
marvel whence came the imperfection. In some cases, the parents and 
possibly the grandparents of the unfortunate children have not displayed 
any obvious evidence of the tendency to disease which they have inherited 
and handed on to their descendants. Not looking farther back, the parents 
boldly assert that such a thing as insanity, epilipsy, scrofula, etc., is un- 
known in their family. They themselves have never been insane, why 
should their children be? In like manner, children may be epileptic, blind, 
deaf-mute, lymphatic, cancerous, criminal, drunkards or deformed from 
direct inheritance and yet the family line be honestly declared healthy. The 
truth of Sir William Aitken 's maxim that "a family history including less 
than three generations is useless and may even be misleading" is hence 
obvious. 

Similarity of temperament induced by a common environment, which 
Strahan calls "social consanguinity" is also a potent factor in degeneration. 
Living under similar customs, habits and surroundings, laboring at the 
same occupations, and indulging in the same dissipation, tend to engender 
like diseases and degenerations irrespective of blood relationship. Persons 
not even distantly related by blood are in reality much more nearly related 
in temperament than cousins or even nearer blood relations who have 
experienced widely different modes of life. The "social consanguinity" 
is the great curse which dogs every exclusive tribe and class and hurries 
them to extinction. It has largely added to real or family consanguinity 
in the production of the disease and degeneration which have fallen so 
heavily upon the aristocracies and royal families of Europe. This "social 
consanguinity" appears likewise in the tendency of the neurotic to inter- 
marry, popularly expressed in the proverb that "like clings to like." 
This marital likeness in mental characteristics has been shown to be 
present by Roller, de Monteyel, Kiernan, Bannister and Manning repre- 
senting Germany, France, the United States and Australia. 

School Strain evinces itself in a systemic nervous exhaustion mani- 
fested along lines of least resistance. The first type of neuroses are due to 
overstrain of certain territories related with memory as constrasted with 



120 DEVELOPMENTAL PATHOLOGY 

diminished use of the association fibers connecting these. In degenerate 
children, because of deficiencies of proper interassociation of the memory 
territories in the brain, healthy curiosity and the instinct of sheltering are 
deficient, so that states of uncertainty, producing terror, result. These 
become permanent in after life, even when training as adults is strongly 
antagonistic to them. Over-pressure in school in certain respects checks, 
even in well-developed minds, the transition from the terror of the un- 
known of childhood into the calm of maturity. Morbid fears, imperative 
conceptions, and imperative acts which torture the individual during an 
otherwise healthy career unquestionably originate in the early periods of 
life. 

Neurasthenia is a common neurosis by which Preston remarks 
males are equally affected with females. It is nerve instability in which, 
in addition to ordinary nerve fatigue, there is a morbid susceptibility to 
emotions and inability to restrain their manifestations. It is apt to make 
its onset near puberty, when permanent teeth are most liable to decay. 
Temporary teeth are frequently badly decayed as a result of child neuro- 
pathy and hysteria. Permanent teeth later in life decay from premature 
senile neuropathy. Neurotic inheritance, aided by the influence of climate 
and race tendencies, and an unstable, badly organized or imperfectly 
developed nervous system, are potent factors in tooth decay. When to 
this are added diatheses like tuberculosis, syphilis, etc., causes for tooth 
decay are enormously increased. Any long-continued disease, grief, fear 
of litigation or death, also cause nerve fatigue, an excessive nerve waste and 
its retention. Anxiety, especially of young children, and between the ages 
of twelve and twenty-four, relative to their standing in school, is a fruitful 
source of nerve tire, nerve waste and faulty metabolism. The forcing 
system of schools adds neurasthenia to the list of accomplishments. While 
"all work and no play makes Jack a dull boy" from nerve tire and self 
poisoning, the same is even more true of Jack's sister. Few universities 
do not have in their faculties fairly typical neurasthenics from pedagogic 
worry and too one-sided life. 

The causes just enumerated are in adults fruitful sources of nerve 
exhaustion. Elsewhere I have frequently shown that any excess is a 
fecund cause of nerve exhaustion. Neurasthenia occurs in every walk of 
life. People raised in luxury and idleness are the most evident victims 
of neurasthenia. Neurasthenia was particularly frequent among the 
second generations of Puritans, whence the Salem witchcraft epidemic and 
the miraculous cures related by John Eliot. The lowest classes, who give 
free rein to the appetites, and the tramps are often neurasthenics, as are 
those between these two, persons who lead a sedentary life to which is 
added severe mental strain, care, responsibility, monotony, anxiety. 



A STUDY IN DEGENERATIVE EVOLUTION 121 

Neurasthenia is frequent among clerks, teachers, literary workers, etc. 
It is often the ancestral phase of degeneracy; through it occurs the rapid 
decay of the teeth in persons over thirty or forty years of age who have 
had very little decay previously. 

Nothing does so much to bring about degeneracy as the exhausting 
social functions undergone by young women just before marriage. Brides 
become so exhausted that they can hardly stand at the altar. Women 
in nourishing their children can not only overcome their own defects but 
likewise those of their husbands. It is, therefore, better for a prospective 
bride to isolate herself and rest rather than undergo the stress of social 
functions in celebration of her approaching marriage. Few women under 
existing methods of life can rear a family destitute of mental and physical 
defect. The same was equally true of past centuries, whence the congeni- 
ally defective ancestors of the present generation. 

Neurasthenia in the parents from all conditions herein enumerated 
affects pathologically the development of the child. This implies a practi- 
cal degeneration in function, since tone is lost. 

Every nerve cell has two functions, one connected with sensation or 
motion and the other with growth. If the cell be tired by excessive work 
along the line of sensation or motion the function as regards growth becomes 
later impaired, and it not only ceases to continue in strength but becomes 
self-poisoned. Each of the organs (heart, liver, kidneys, etc.) has its 
own system of nerves (the sympathetic ganglia) which, while under the 
control of the spinal cord and brain, acts independently. If these nerves 
become tired the organ fails to perform its function, the general system 
becomes both poisoned and ill-fed and nervous exhaustion results. In 
most cases, however, the brain and spinal cord are first exhausted. The 
nerves of the organ are then allowed too free play and exhaust themselves 
later. This systemic exhaustion has local expression in the testicles in the 
mate, in the uterus and ovaries in the female. Because of this condition 
the body is imperfectly supplied with the natural antitoxins formed by 
the structures; the general nervous exhaustion becomes more complete 
and all the organs of the body are weakened in their functions. Practically 
the neurasthenic in regard to his organs has taken on a degenerative func- 
tion, although not degenerating in structure, since the restlessness of the 
organs is a return to the undue expenditure of force which occurs in the 
lower animals in proportion as it is unchecked by a central nervous system. 
Through the influence of various exhausting agencies, the spinal cord and 
brain lose the gains of evolution and the neurasthenic is no longer adjusted 
to environment. Since the reproductive organs suffer particularly, chil-. 
dren born after the acquirement of nervous exhaustion, more or less checked 
in development as the influence of atavism is healthy or not, repeat degen- 



122 DEVELOPMENTAL PATHOLOGY 

erations in the structure of their organs, which in the parent were repre- 
sented by neurasthenic disorders in function. As the ovaries of neuras- 
thenic women generally exhibit prominently the effects of the nervous 
exhaustion, the disappearance of the centrosome is not properly affected 
and sufficient stimulus by the spermatozoon is not secured and the off- 
spring of these do not gain vigor to pass through the normal process of 
development. 

Summary 

The normal checks on excessive functionation and development are 
subject to two classes of demoralizing influences: (1) relaxations of all 
kinds and (2) various disease-producing agencies. 

In the first class are included excesses, toxic agents, contagions and 
infections, heredity, consanguinous and neurotic marriages, school strain, 
and neurasthenia in parent and child. 

In the second class are various drugs, improper food, drink, certain 
occupations, worry, etc. 

Tobacco, alcohol and opium vie with each other in their ill effects 
upon the human economy. Tea, used in excessive quantities, has similar 
effects to tobacco and alcohol. Coffee induces stomach and bowel dis- 
turbances which ultimately affect the nervous system, heart, etc. The 
chewing of the coca leaf and, in civilized countries, the use of its alkaloid, 
cocaine, have produced many degenerates. Lead, brass and mercury 
cause profound nerve tire, appearing as degeneracy in the offspring. 

The contagious and infectious diseases produce grave constitutional 
defects which cannot be overestimated. The great crusade now being 
waged against tuberculosis may help to minimize this danger. And finally, 
traumatism and isolation are factors in the increase of degenerative condi- 
tions. 

The underlying principle by which all of these influences produce 
degeneracy is that they disturb the physiologic balance between the local 
nervous system of the various cell-groups and organs and the central 
co-ordinating nervous system, thus creating among the former a struggle 
for existence, excessive nerve action, and ultimately exhaustion. 

The effect of these disturbances as exercised through heredity involves 
exceedingly complex processes and phenomena. Fundamentally, they 
may all.be reduced to a lack of the necessary ancestral impetus required 
to carry the organism through the various stages of its development, with 
their successive periods of stress. Such hereditary defects are sometimes 
overcome by the superior strength of the maternal parent, and, as previous- 
ly explained, atavism (reversion to ancestral types) continually modifies 



A STUDY IN DEGENERATIVE EVOLUTION 123 

direct heredity. The phases of heredity commonly observed and considered 
are those of direct parental influence only. But, as Sir William Aitken 
has said, "a family history including less than three generations is useless 
and may even be misleading." 

Heredity, therefore, is not a fixed inevitable destiny of what must 
occur, but a sum of possibilities of what may occur, and these possibilities 
are affected by the check-disturbing influences which are here considered. 
Many degeneracies are attributed to heredity which are in reality brought 
about by intrauterine periods of stress and the environment of the mother 
during gestation. On the other hand, physical, mental and moral degen- 
eracies may be inherited from a remote ancestor, their effects having re- 
mained latent in intervening generations by virtue of compensating 
influences. 

Consanguinous marriages disturb the physiologic balance because 
of the accentuation of parental qualities, which ought to be balanced by 
dissimilar qualities. School strain, by its undue concentration of nervous 
control in certain directions, deprives other important structures and 
functions of their necessary normal check, and thus leads to physical and 
mental degeneracies. 

To sum it all up, one of the essential phases of upward development 
in an organism, as in a social body, consists in the greater and greater 
subordination of local nerve centers to the central co-ordinating system; 
and any influence which disturbs this co-ordinating process, to the extent 
of causing excessive local action at the expense of the whole, to that extent 
puts the organism back into the condition of a lower type of development 
and constitutes a degeneracy. Normally, the higher potentialities gain 
at the expense of the lower ones; but when normal check action is disturbed, 
the lower gain at the expense of the higher, hence the later acquired organs 
and functions are most likely to be affected by such degeneracies. 



Chapter XI 
NERVOUS EFFECTS OF RELAXED CHECK ACTION 

The influence of the maternal nerves on the development of the fetus 
is a fact of clinical experience, although the manner in which it is exerted 
has not been made clear. Whatever may be the truth regarding maternal 
impressions, there is decided reason to believe that anxiety, neurasthenia, 
nervous diseases and autointoxication of the mother affect the growth of 
the fetus. 

Maternal Influence Upon Nutrition. Some recent investigations 
in metabolism afford a possible explanation in the influence of the nervous 
system of the mother on the nutrition of the fetus. It has been shown 
that in the case of certain seeds, the nourishment stored up in the albumen 
of the seed is of a specific nature peculiar to that species. This indicates 
that the embryo, in building its tissues, must use material derived from an 
organism of the same species. It is probable that the cells, in developing, 
build up their protein constituents from comparatively simple amino acids 
that are peculiar to the species to which the cells belong. It may be 
possible that each tissue and organ needs for its development its peculiar 
protein, made up of amino acids different from those found in other parts 
of the body. This points to the probability that the materials for the 
growing fetus must be furnished by the breaking down of the maternal 
tissues. That such a breaking down of the maternal tissues takes place 
in pregnancy is shown by recent experiments. Such a decomposition, 
without doubt, takes place under the influence and regulation of the 
nervous system. If this be the case, it is easy to see how derangement 
of the nervous system by disease or by unfavorable psychic influences may 
alter the composition of the material supplied to the fetus and so affect 
the development of the fetus in general and perhaps also that of particular 
organs. Sickness and even death of the child has been known to occur 
by the agency of poisons produced in the breast milk through the agency 
of powerful emotion in the mother. If such a mishap may occur to the 
growing child, it is easy to understand that a like occurrence might happen 
to the fetus from the action of poisons generated by the nervous system 
of the mother and conveyed to the embryo or fetus by the blood. A 
direct nervous connection between mother and fetus does not exist. How 
much influence may be conveyed by the tissues not having nervous struc- 
ture is not known and although such influence is possible, it is undoubtedly 
slight and quite indefinite. 

124 



A STUDY IN DEGENERATIVE EVOLUTION 125 

Influence of Fetal Nervous System. Little is known of the 
nervous system of the fetus on its own development, but arguing from 
the analogy of what happens in extrauterine life, we conceive it to be 
great. Some nervous diseases are congenital and must have begun in 
intrauterine life and the infant at birth often exhibits the results of intra- 
uterine nervous disease, particularly of a syphilitic nature. It is, therefore, 
not reasonable to attribute much of the developmental defects observed 
at birth to perverted action of the nervous system of the fetus. 

Fetal Nervous Diseases. The diseases of the nervous system of 
the fetus are due either to germs, as those of tuberculosis or syphilis, 
introduced from the paternal organism with the semen, or to similar germs 
or poisons introduced by the maternal blood. Poisons may be foreign to 
the system of the mother reaching her through the food or they may be 
the result of putrefaction in the intestines, intestinal autointoxication or 
may arise from the metabolism of her own tissues. As most derangements 
of the maternal nervous system are the results of autointoxication, it is 
easily understood how such influences may effect the nervous system of 
the fetus and hinder the development or cause degeneration of various 
parts of the body. 

After birth, many instances of disturbances of nutrition occur which 
have their origin in altered nervous function. 

Classification of Nervous Diseases. The diseases of the nervous 
system may be ranged in three classes so far as their etiology and pathology 
is concerned. 

(a) Organic diseases in which the function of a part of the nervous 
system is more or less permanently suspended because of organic changes 
in the nerve itself or in the surrounding tissue. These changes are some- 
times of an inflammatory nature like myelitis, neuritis, meningitis, etc. 
At other times, the change is pure degeneration of the nervous substance 
with little or no inflammatory reaction. The inflammatory changes are 
brought about by infectious agents, the degenerative by poisons of a non- 
infectious character. In either case, the function of the nerve or ganglion 
cell is suspended for a longer or shorter time with a corresponding effect 
on the nutrition of the parts supplied by the corresponding nerve fiber. 
If the nerve trunk be affected, degeneration of the muscle occurs, followed, 
in some cases, by a slow regeneration when the poison has been eliminated. 
Such is the result of the neuritis that ensues after the ingestion of alcohol, 
arsenic or allied poisons. A good example is seen in the head palsy, where 
the nerves supplying the extensor muscles of the forearm are degenerated 
and the muscles become paralyzed and waste away, giving the phenomena 
of wrist drop. A similar phenomenon is seen when a nerve is compressed 
as by the pressure of one bone on the other. A familiar example is seen 



126 DEVELOPMENTAL PATHOLOGY 

in Potts' disease of the spine. The nerves compressed between the dis- 
torted vertebrae degenerate and the muscles atrophy. If, however, the 
pressure is relieved, a regeneration occurs and the muscles are restored to 
their former state of nutrition and functional activity. If sensory nerves 
are affected, the skin suffers and bedsores, ulcers, etc., occur. A good 
example of this influence of the nerve on nutrition is seen in the perforating 
ulcer of the foot which frequently occurs in locomotor ataxia, a disease in 
which the essential lesion is a degeneration of the sensory ganglion cells 
of the spinal nerves and the tracts of the cord connected with them. In 
cases in which the ganglion cell is affected the paralysis and atrophy of 
the muscle are permanent. 

(b) A second etiology of nervous disease is the action of poisons 
which produce no recognizable organic change. Such diseases may vary 
largely in their manifestations at different times. Epilepsy, urticaria, 
angioneurotic edema, asthma, and a number of neuroses of various organs 
are of this character. Their influence on nutrition is not so clearly traced 
as in the former case. 

(c) A third class of nervous diseases owe their origin to psychic 
causes or are accompanied by marked changes in the mental state. These 
states are mainly grief, worry, nervous breakdown, hysteria, neurasthenia, 
psychasthenia and the psychoses. Their influence on general nutrition 
is sometimes very marked. 

Thus, emotion has been known to change the color of the hair, initiate 
serious disturbances in metabolism, affect the teeth so that they decayed 
very rapidly and produce marked changes in nutrition. 

Infectious diseases even when they do not especially affect the nervous 
system provoke marked disturbance of nutrition. The growth is checked 
and development is very unfavorably influenced. The hair falls out after 
many fevers and white areas in the skin and nails are noticed in many 
instances. Similar changes occur in the teeth. 

The sensory nerves have some control over the nutrition of the skin 
and its appendages through their vasomotor influence. Nervous influences 
may cause marked changes in the parts supplied by the sensory nerves. 
Various skin diseases are simply expressions of action on the nerves. 
Herpes follows the course of a nerve and evidently depends on some cause 
affecting the nervous system. This may be a toxin such as that of pneu- 
monia which is frequently accompanied by herpes of the lip or it may be 
a disease causing primary pathologic changes in the nerve itself such as 
neuritis, meningitis, etc. The erythemata are other manifestations of 
perverted nervous action. Other dermatoneuroses occur; even eczema 
is often due to neurotic action. 

Vasomotor Control. All the internal organs are supplied by the 



A STUDY IN DEGENERATIVE EVOLUTION 127 

sympathetic nerves which control the actions of the viscera and regulate 
the blood supply of the entire body through the vasomotor nerves which 
accompany the arteries and regulate the caliber of the smallest . blood 
vessels. So great may be the influence of this nerve on nutrition that 
gangrene may occur under the influence of certain poisons that act especial- 
ly on it. Unknown poisons may disturb its action so as to produce similar 
results. This is the case in Reynaud's disease, in which a spasm of the 
smaller blood vessels is brought on by some toxin, the nutrition of the 
parts affected is suspended, and gangrene occurs. Asthma, angioneurotic 
edema and edema of the lungs are other examples of pathologic conditions 
that may be brought about by abnormal action of the sympathetic nerve. 

Obesity and Leanness. Evidences of the effect of the nervous 
system on general nutrition are further seen in the disposition to obesity 
or to emaciation. It is generally noticed that obesity and leanness are 
characteristics of certain families. Differences of disposition also accom- 
pany the two states. The lean people are usually active in intellect, 
inclined to worry and anxiety; the corpulent are usually easy going, often 
slow of action and sometimes dull in intellect. The two conditions are 
to be regarded rather as the effects of the action of the differently constituted 
nervous system for we often see the emaciating effects of an excited or 
diseased brain. 

Special changes in metabolism are also occasioned by the action of 
the nerves. Certain cases of diabetes and albuminuria are due to the 
growth of tumors in the fourth ventricle. Glycosuria can be produced 
by a puncture of a certain part of the floor of the fourth ventricle. Dia- 
betes can often be traced to the influence of grief, anxiety, etc., which 
without doubt, act through the nervous system. 

Summary 

Just how maternal impressions affect the unborn child has not been 
intelligently explained. It is a well known fact, however, that grief, 
worry, disease and environment of the mother affect the development of 
the child. It is probable that the proper breaking up of the maternal 
elements of nutrition depends upon normal nervous control, and disturb- 
ance of this control results in vitiated fetal nutrition. 

Severe illness and even death of the nursing child have been known 
to occur through the emotions of the mother, and the same condition in 
utero could occur through the action of the blood, since there is no direct 
nerve relation between mother and unborn child. 

To judge from the influence of the nervous system upon development 
after birth, a great influence must be exercised on the development of the 



128 DEVELOPMENTAL PATHOLOGY 

fetus by its own nervous system. Many nerve troubles have their origin 
in utero, especially is this true of the contagions and infections. In fact 
many diseases of the fetal nervous system may be traced directly to this 
source. 

There are three classes of nervous system diseases in regard to their 
etiologj' and pathology: 

(a) Those in which the essential morbid element consists in a structu- 
ral change in the nerve tissues, such as inflammation and degeneration. 

(b) Those in which certain toxic agents affect the functionation of 
the neurons without producing any recognizable structural changes. 

(c) Those which originate in purely psychic and mental conditions. 
Disturbed nutrition is a prime result of demoralized nerve action. 



Chapter XII 

CONSTITUTIONAL DEGENERACIES DUE TO CHECK 

ACTION 

Of Normal Structures in Man's Present Evolution 

CONSTITUTIONAL degeneracy due to increased check action may 
be considered under three heads; first, those degeneracies which in- 
volve the normal structures in the existing stage of evolution as they 
pass through the periods of stress; second, those involving structures which 
were useful in adult lower vertebrates but only embryonic in man which 
Shute calls "useless scaffolding left in the body"; and third, involving 
those structures which are disappearing. 

Before considering these types, it is necessary to have a clear under- 
standing of what a degenerate is and what degeneracy means. 

A Degenerate, then, is one with an unstable nervous system and 
whose physical development is a departure from the type, in the direction 
of lessened complexity. 

An Unstable Nervous System is one in which higher centers are 
arrested or over-developed, either as a whole or as to powers of co-ordina- 
tion, a fair sample of which is found in a one-sided genius or a moral imbe- 
cile. 

Physical development departs from the normal when an organ or 
part of the body has become arrested or excessively developed at the 
expense of the whole organism. 

An unstable nervous system may exist with all structures and organs 
normally developed, thus moral imbeciles and paranoiacs occur with nor- 
mally developed structures. Here the structures and organs have gained 
at the expense of the central co-ordination of the nervous system. 

Persons, having normal brains, may have degenerate organs and 
limbs; successful and mentally well-balanced men may have degenerate 
structures and organs. The higher nervous system has here gained at 
the expense of other structures. 

A man is not necessarily a degenerate in the complete sense of the term 
because he possesses stigmata. Certain Italian and French viewpoints 
make a man a degenerate with eight or twelve stigmata, irrespective of 
the nervous normality present. 

A Degeneracy is a badly balanced structure, arrested or excessively 
developed, or both. Degeneration is a gradual change of structures by 
which the organism becomes adapted to less varied and complex conditions 
of life. 

129 



130 DEVELOPMENTAL PATHOLOGY 

Degeneracies in children take place at periods of stress because the 
nerve centers are then not properly co-ordinated and therefore unstable. 
Such degeneracies may remain throughout life and the brain later develop 
to normal. Degeneracies from post-natal causes may take place at the 
periods of stress even though the nerve centers of the previous stage be 
normally developed. 

Nearly every kind of physiologic disturbance may occur at periods 
of stress from the influence of maternal nutrition, environment, personal 
congenital factors, or, after birth, from the infections. 

Organs and structures checked at certain phases of development often 
pursue a course of development differing from that indicated in man, but 
allied to that designated in other vertebrates. 

Stigmata. Degeneracy may be limited to certain signs which are 
its sole expression. These signs (stigmata) may be the only expression of 
degeneracy. Their true significance must be determined by a careful 
examination of the organism in which they are found, since they may be 
merely external defects produced by degeneracy, or may indicate how 
deep such degeneracy has penetrated. They may indicate slight or serious 
defect. In proportion to the depth of degeneracy, in the organism, will 
the stigmata affect the earlier or later complex states acquired through 
evolution. 

Of necessity, when the organism is affected by degeneracy, the morbid 
process will take the line of least resistance, determined by the depth of 
degeneracy, as well as by the variability of the structures concerned and 
the nature of maternal and personal environment. The same influence 
equally affects functions of the structures. Expressions of degeneracy 
will be influenced by the periods of stress. These stigmata, generally 
speaking, are divisible into mental and physical. They are best observed 
in their relations to the periods of stress. In certain races, as in certain 
animals, pre-puberty conditions cannot be considered as settling the posi- 
tion of the animal in the scale of life. What is true of individuals is also 
true of classes. Anthropoid apes and negroes are much higher in physical 
characteristics, with potential and mental results, before puberty than after. 

Artificial or accidental periods of stress may be produced, when the 
natural course of development would be otherwise uneventful, by disease, 
by intoxication, by various impunities of food, drink, infections, or by 
nervous changes resulting from mental anxiety or other emotional cause. 

Nutritional Aspect of Development. Development of organs is 
markedly influenced by their functional activity. Increased function is 
followed by increased nutrition and by evolutional perfection of the func- 
tioning organ. This may cause a transmission of new characters to the 
offspring. Disuse leads to atrophy (arrest of development) but only after 



A STUDY IN DEGENERATIVE EVOLUTION 



131 



a long period of disuse by successive generations do the apparently useless 
organs cease to appear. Degeneracy of some organs may be necessitated 
by the development of others. Thus prehensile development of the hand 
renders it less useful for locomotion. The reverse occurs in the foot. 
Development of the brain, by which inventions are created to do away 
with manual and physical labor, results in subordination of the physical 
man to the mental. 

Because of the reversional aspect of physiologic atrophies and hyper- 
trophies, Magnon and Legrain made the true but too radical assumption 
that degenerates are abnormal because of the inability to re-acquire 
progressive powers of primitive ancestors. There are here two factors, 
independent of the enormous one of environment, to be considered, viz., 
the impetus given nutrition toward the hypertrophied organ and the 
impetus of nutriment from the atrophied organ. For this reason evo- 
lution retrogression involves more than the simple retracing of the steps 
of normal evolution. This principle is illustrated in the diagrams of 
Magnon and Legrain, Fig. 63. The ascending lines represent the pro- 





FlGURE 63 

Diagram showing progressive and degenerative evolution of a structure or organ, 
(Magnon and Legrain). 



gressive evolution of an organ or institution; the descending lines represent 
the degenerative or suppressive evolution. From the point a, representing 
the primitive condition, progressive evolution passes toward o, an imag- 
inary perfect condition of the organ. Along the upward line, however, 
the points a, b, c, d, etc., represent obstacles to further progress — that is 
to say, factors tending toward degeneration. From these points lines of 
degeneration pass towards z, and the condition at z, although equivalent 
to that at a, is not identical with a, and is not reached by a sliding back- 
wards down the line o-a. Thus, while most recently acquired features 
tend to disappear first, degeneration is not a complete retracing of steps 



132 DEVELOPMENTAL PATHOLOGY 

until the point of departure is reached, else arrest in development would 
result in complete annulment of all further progress. 

In the evolution of the frog from the tadpole, certain structures are 
lost and others gained. This is true of all animals. By the permanent 
laws of nature, an animal must adapt its organism to its environment or 
become extinct. These structural changes take place according to environ- 
ment. The same condition is true of man. In his evolution, man under- 
goes changes to suit his environment. Structures are lost and others 
gained to meet these requirements. This law, indicated by Aristotle, 
but clearly outlined by Goethe in 1807 and Geoffroy St. Hilaire in 1818, 
underlies the physiologic atrophies and hypertrophies which play such a 
part in degeneracy and evolution. Structures that are passing are called 
transitory or degenerate structures. Transitory or degenerate structures 
are more easily and quickly affected by disease than those which are 
gaining in function. 

Evolutional Phases of Degeneracy. Specialization oftentimes 
results in further development of organs or parts; or certain organs or 
parts are used for other purposes changing their original form; or certain 
organs or parts disappear by atrophy. When these developments fail, 
abnormalities appear resembling those of the invertebrate and vertebrate 
types. Structures normal in invertebrates and vertebrates may remain 
in a rudimentary condition; or a structure normally transformed may 
retain its original form; or, finally, structures which normally perish by 
atrophy may fail to do so, and a fully-developed organ, normal in the 
lower animals, may thus atavistically reach full development in man. 

Close study of degeneration shows why anatomic characteristics of 
man and apes are so intimately allied. Not that man sprang from the 
ape (though they have identical structures some of which are lost by 
atrophy or remain dormant in man) but that they have a common ancestor, 
which had the structures normal in the apes but atavistic in man. As 
already shown, every structure in the human body passes during its ontog- 
eny through stages of the lower vertebrate types, fish, reptile, bird and 
mammal. Arrest or excessive development may occur during the period 
of stress at any one of these stages. Only a few of the more marked 
changes will be here considered. 

Constitutional degeneracies, due to check action of normal structures 
in man's present evolution, include: durencephaly, degeneracies affecting 
bones of the body as a whole, the brain, neurons and connecting fibers, 
the hair, gill clefts and defective ears, supernumerary mammae and nipples, 
internal organs, uro-genital cleft, uterus and ovaries, non-descent of the 
testicles or cryptorchidism, degeneration of the bowels, spina bifida, 
deformity of the hip joint, club foot and hands, flat foot and obesity. 



A STUDY IN DEGENERATIVE EVOLUTION 



133 



Durencephaly. Degeneracy which involves the normal structures 
of the body in the present stage of evolution as they pass through the 
periods of stress may begin in the prevertebrate types (Fig. 64). The 




Figure 64 

Durencephalous head of new-born child (original). This illustration shows an arrest in 

ontogeny of the cranium with an elephantine ear. 

primary skull, as already stated, is an extension of the vertebrae, which 
send side outgrowths to cover the brain, as the backbone covers the spinal 
cord. In the lancelet, it gives off two trabeculae cranii or front skull 
plates. In the back, the primary skull (or chondrocranium) gives off two 
occipital or rear skull plates and two plates midway between the trabeculae 
and the occipital. These gradually close the primitive hearing apparatus, 




Figure 65 
Arrest of development of the entire body at eight years of age due to scarlet fever. The fig- 
ure to the right, now forty-two years of age, contrasted with a normally developed man. 



134 



DEVELOPMENTAL PATHOLOGY 



the otocysts (permanent in fish and embryonic in man) and are called 
periotic capsules. This primary skull is at first cartilaginous, as in sharks. 
With increase in size of the brain, in biologic evolution and in human 
embryogeny, the cartilaginous primary skull becomes insufficient to roof 
over the brain and gaps result. The extent of these gaps depends upon 
the amount of nutriment furnished by the mother for the development of 
the fetus. If sufficient material be not furnished, fontanel] es and open 
spaces (Fig. 33) in the skull result. Often these spaces are filled with 
imperfect bone types, the Wormian bones (Fig. 34). The amount of 




Figube 66 
Figure to left, skeleton of a female cretinoid dwarf. (Age 31, height 118 centimeters) (Zieg- 
ler). The epiphysial cartilages of the long bones and pelvic bones persist, as also the 
frontal suture. The several parts of the skeleton are fairly proportionate, except that 
the upper extremities are relatively short. Figure to the right, skeleton of a female 
dwarf. (Age 58, height 117 centimeters). The bones of the limbs are very short, the 
trunk is relatively long. The epiphysial cartilages have not persisted, and the articular 
ends of the bones are thickened. 



A STUDY IN DEGENERATIVE EVOLUTION 



135 



nutritive material may be so scanty that the entire dome of the skull 
remains undeveloped (Fig. 53). 

Degeneracies Affecting Bones of the Body as a Whole. Arrests 
of the body as a whole may take place in utero from the unstable nervous 
system of the mother, her imperfect nutrition or autointoxication. Arrests 
of the child after birth often arise from constitutional diseases, more 
particularly the eruptive fevers. All constitutional diseases affect children 
to a greater or less degree, sometimes for a week, month, year or for life. 
Fig. 65 shows a person forty-two years of age whose development became 
arrested at eight from scarlatina. Different parts of the body are often 
disproportionately developed. Thus the trunk may be arrested or ex- 
cessively developed (Fig. 66). The limbs may be short or long to cor- 
respond with deficiencies or excesses. The bones upon one side of the 
body may be larger than on the other. Occasionally the limbs are unusual- 
ly short, the hand may be developed at the elbow or shoulder, the foot at 
the knee or hip. These arrests simulate the flipper of the seal or whale. 
Excessive development of the arms is sometimes noticed, they often develop 
to the extent that the tips of the fingers extend below the knee as in apes, 
Fig. 67. 







a. 



b. 



Figure 67 
Skeleton of anthropoid apes and man (Huxley), (a) orang; (b) chimpanzee; (c) gorilla; 
(d) man. The contrast and evolution of the head and jaws is striking. The front legs 
or arms are also noticeable in regard to length. The shortening of the fore limbs as 
we advance in evolution, due to environment, is pronounced. 



136 



DEVELOPMENTAL PATHOLOGY 



The human limbs are developments from the fin-folds as found in 
fish, reptile, bird and mammal. In one of these, the fins are divided into 
four segments. The upper segment contains one long bone, the humerus 
(or arm bone), or the femur (or thigh bone). The second segment con- 




FlGURE 68 

The evolution of the limbs from the fin (Carnegie Museum). (1) is the fin of the fish. The 
rays are numerous, many jointed, slightly flexible and capable of lateral movement 
only. The arm bones are short, broad and thin and the entire organ is so constructed 
that it is only adapted for swimming purposes. (2) The swimming paddle of the 
dolphin in which the phalanges are separated from one another by intervening cartilages 
and on the elasticity of which the mobility of the manus depends. The radius and ulna 
are parallel to each other capable of rotation. (3) The bones in the wing of the bird 
adapted to flight only. The humerous articulates with the radius and ulna by a slightly 
oblique joint. There is practically no rotation of the manus and in this part the carpal 
bones are reduced in number. All the bones of the limb are evidently adapted for 
supporting the quill feathers and for free flexion only in the direction of folding or 
extending the wing. In (4) that of the lion, the entire mechanism of the foot is developed 
to produce a rapid, light and springy gait and to protect the tips of the claws from 
unnecessary wear. (5) Prehension in which is attained the greatest possible mobility 
compatible with the presence of long inflexible bones is well typified by man. All 
the joints are so arranged that the hand is capable of movement in most any direction. 
While there is a similarity in each limb, each has developed for some particular purpose. 
The purpose, however, is more complicated, the higher the advance in phylogeny. 



A STUDY IN DEGENERATIVE EVOLUTION 137 

tains two long bones, the radius and ulna (or forearm bones), or the tibia 
and fibula (or leg bones). The third segment consists of nine small bones, 
the carpals of the wrist or the tarsals of the ankle. The fourth segment 
consists of five separate digits. These limbs pass through stages in phvlo- 
genetic development according to their position, shape> length and function 
which may be designated as fish, reptile, bird and mammal types, Fig 68. 
Many of these bones fuse together (carpals and tarsals). The digits have, 
long before the fish stage, been formed of more than one bone. At times, 
this condition persists even after the completion of human embryonic 
development. Limb anomalies resulting from checks of development 
causing either excess or arrest of development are far from uncommon in 
degenerates but are not so common as anomalies of form and proportion, 
Fig. 69. 




Figure 69 
"Pepin" (Gould and Pyle). The hands and feet are fairly developed while the bones of the 
arms and legs are arrested in phylogeny. 

Sometimes the arms develop completely while the lower extremity 
remains in the fin-fold state. On the other hand, the arms may be checked 
and remain in the fin-fold state while the legs go on to full development. 
Sometimes the bones of the arms and legs are checked while the digits go 
on to full development. The lower extremities are sometimes fused to- 
gether. This condition, from its resemblance to the like state in the seal, 
is called phocomelia or seal limbs, Fig. 70. 

Achondroplasia, or imperfect development of cartilage with resulting 
imperfections in the extremities, sometimes occurs. A man of thirty- 



138 DEVELOPMENTAL PATHOLOGY 

eight years, had a face arrested in development producing the appearance 
of a ten-year-old boy. His jaws were small with a protrusion of the lower. 




Figure 70 
Example of siren (Gould and Pyle) . Shows fusion of the lower extremities. 

His arms were absent. The hands were full sized and attached to the 
shoulder. In a member of the Spanish nobility, degeneracy was stamped 
on the entire body. He was short in body and had an enormous head. 
The jaws were undeveloped with a V-shaped arch. His left hand was 
located near the shoulder. 

Supernumerary fingers and toes are not uncommon. Darwin regarded 
them as atavistic. 

The Brain, Neurons and Connecting Fibers. The most marked 
distinction between man and the lower animals is in his brain. In man, 
this higher organ has grown to be three times larger than the brain of the 
highest apes. 

With a cerebral surface, and a corresponding intelligence, far greater 
than that of other mammals, anthropoid or tailless apes begin life as help- 
less babies and are unable to walk, to feed themselves, or to grasp objects 
with precision until they are two or three months old. At this period, 
they are able to care for themselves. These apes have thus advanced a 
little way upon the peculiar road which the forefathers of man began to 
travel as soon as psychical variations came to be of more value to the 
species than variations in bodily structure. The gulf by which the lowest 
known man is separated from the highest known ape consists physiologically 
in the great increase of his cerebral surface, with the corresponding increase 
of intelligence, and in the very long duration of his infancy. These things 



A STUDY IN DEGENERATIVE EVOLUTION 



139 



have gone hand in hand. Increase of cerebral surface has entailed a vast 
increase in cerebral organization that must be completed after birth, 
which thus has prolonged the period of infancy. Conversely the pro- 
longing of the plastic period of infancy, entailing a vast increase in teach- 
ableness and versatility, has contributed to the further enlargement of the 
cerebral surface. These mutual re-actions have gone on for an enormous 
length of time, since man began diverging from his simian brethren. 

Reversions and defects in brain growth are numerous. The classifi- 
cation of brain defects has been discussed in Chapter IX. In passing, 
it is only necessary to say that brain arrests and excessive development 
take place like those of any structure in the body. Excesses or arrests 
as a whole, in brain areas, in nerve cells, or in connecting fibers render 
him more highly developed or cause simulation of the lower vertebrate 
types. Even the cells of the cortex, with their prolongations, pass through 
the fish, reptile and bird types in their development. The folds of the 
cerebral cortex, from a lack of healthy normal stimulus, sometimes revert 
to forms resembling those found in other groups of the animal kingdom. 

Hair. In the development of the fetus from the fifth to the seventh 
month, the body, except the palms of the hands and the soles of the feet, 
is covered with a thick hairy coat. It is claimed this coat is shed at birth 
but whether this be true or not, there is a coat of fine short hair over the 
body throughout life. This covering is called lanugo and is atavistic, 
since the apes (man's nearest ancestors) have hair over the entire bodv; 





Figure 71 
Excessive hair growth (Ziegler). 



Figure 72 
Jo-Jo" (Gould and Pyle). 



it is therefore a simian characteristic. All human beings have an exces- 
sive development of hair on different parts of the body, occasionally 
developing to large proportions. When man passes through the first 



140 DEVELOPMENTAL PATHOLOGY 

period of stress, arrest takes place at the anthropoid ape stage and the 
hair develops at the expense of other organs (Fig. 71), where it simulates 
the lower ape. There are many noted instances of this development. 

Some years ago, a person exhibited under the name of "Jo- Jo, the 
dog-face boy" (Fig. 72), had a true sky terrier face. A child, a native of 
Indo-China named Krao, had her entire body covered with black hair. 
Many other similar cases are on record. 

True alopecia (the condition of being born without hair), while it is 
rare, does occur. Thus Danz knew of two adult sons of a Jewish family, 
who never had hair or teeth. A number of other cases are mentioned by 
Gould and Pyle. 

Gill Clefts and Defective Ears. The failure of a structure to 
become suited to new uses is seen in the persistence of gill clefts. These, 
serving the fish to admit water holding air in solution, change to other 
structures in air breathing animals. When the adaptation fails, the anom- 
aly of an opening through the neck into the throat is exhibited. An 
attempt to swallow liquids causes them to pass through this opening, thus 
illustrating how a phase of evolution useful and necessary in fish and 
amphibians is a serious danger when it occurs in man. 

Man, in his evolution from the lower metazoa, passed through the 
fish type stage. The breathing apparatus of the fish consists of gills with 
bars across them upon which fleshy curtains are hung, through which blood 
circulates. These bars or arches are from five to seven in number in many 
fish. These slits are open and unprotected in sharks. In modern fish, 
they are protected by a lid. When the fish-like ancestors of man left 
the water, this elaborate breathing apparatus was no longer needed for 
respiration. The first gill slit and portions of its adjacent bars were 
completely changed for the purpose of hearing. Human ears, therefore, 
were in this manner developed. There are two passages in connection 
with the ear; the external auditory canal extending to the membrane or 
drum and an internal passing from the throat towards the drum. These 
canals are similar to the first gill slit of the shark. In degenerates, the 
external ear may be entirely wanting, an opening alone being present. 
The ear may be normal and the opening, with a supernumerary ear, be 
located lower down the neck at one of the other gill clefts. 

The external ear, is, of all organs, most commonly affected by degen- 
eracy. Being a cartilaginous organ extending from a bony base, without 
a bone frame-work for its support and with very deficient blood supply 
owing to its distance from the great blood centers, any defect in the nerve 
centers which control the local blood supply is likely to affect its nutrition. 
On account of its being a cartilaginous organ, it has no lymphatics, necessar- 
ily affecting its growth. The sensitiveness of the ear to vasomotor changes 



A STUDY IN DEGENERATIVE EVOLUTION 



141 



is evident by the results of the extremes in heat and cold, emotional blush- 
ing and fatigue. Galton reports a school mistress who judges the fatigue 
of her pupils by the conditions of their ears. If the ears be white, flabby 
and pendant, the children are much fatigued. If they be relaxed, but red, 
they are suffering, not from over- work, but from a nervous system struggle 
rarely under control in children. These states are common among degen- 
erates. 

To appreciate the degeneracy observed in the ear, its embryogeny 
must be studied. Before the end of the first month, there appears around 
the external opening of the first gill-clefts, a series of six tubercles, two in 
front on the hind edge of the first visceral arch, one above the cleft and 
three behind it (Fig. 73). A little later a certical furrow appears down 




Figure 73 
Development of the ear (Minot). Shows the successive changes in embryonal ear 

development. 

the middle of the hyoid arch, in such a way as to mark off a little ridge 
which joins on to tubercle three and descends behind tubercles four and 
five. The second stage is reached by the growth of all the parts; the 
fusion of tubercles two and three and the growth of the ridge down behind 
tubercle five to become continuous with six. After these changes, it is 
not difficult to identify the parts. 

Tubercle number one is the tragus; two and three together with the 
arching ridge, represent the helix; four the anti helix; five the anti tragus 
and six the lobule; the pit between the tubercles the fossa angularis. 
During the latter part of the second month, the ear changes in its propor- 



142 DEVELOPMENTAL PATHOLOGY 

tion somewhat in the irregular development. The third stage begins 
at the third month. The upper and posterior part of the concha arises 
from the surface of the head, and gradually but rapidly bends forward so 
as to completely cover the anti-helix and the upper portion of the fossa 
angularis. During this stage in mammals, the assumption of the pointed 
form of the ear commences. The fourth stage begins at the fourth month, 
when the tubercles, which are now joined together by cartilages, commence 
to unfold and are completed by the fifth month. Finally, the sixth tubercle 
develops to form the lobule. This unfolding or development of the tuber- 
cles to produce the different portions of the ear and make it complete is 
not unlike the development of a flower from the bud. By this process 
may be understood how if, by malnutrition in one tubercle or bud, or 
should there be a larger supply of nutriment in one than another, mal- 
formation of the ear would result. If arrest of development of all the 
tubercles should take place at any period, from the first to the fifth month 
of fetal life, the ear would resemble a semi-developed flower. 

As in other cases, it is necessary to fix an approximately normal 
standard for the ear from the standpoint of man's status in evolution. 
The ear grows more or less through life, but, like the skeleton, practically 
reaches its full development about the twenty-fifth year. 

A normal ear (or rather the ideal ear, for few possess it in its entirety,) 
should have a gracefully curved outline, nowhere pointed or angular, with 
a well defined helix, separated from the anti-helix by a distinct scaphoid 
fossa extending down nearly to the level of the anti-tragus. Its root 
should be lost in the concha before reaching the anti-helix. The anti- 
helix should not be unduly prominent and should have a well marked 
bifurcation at its superior extremity. The lobule should be shapely, not 
adherent or too pendulous and free from grooves extending from the 
scaphoid fossa. The whole well shaped and properly proportioned. In 
the adult, we may say that it ought not to average much over two and 
one half inches in length and one and one fourth in breadth. 

It is very rare to find a normal ear. The most marked deformities 
are those in which they resemble the ears of lower animals. Thus in 
Figs. 64 and 74, we have the elephantine ear; in Fig. 75, the Darwinian 
ear with the pointed outer or inner rim. Darwin, struck by the frequency 
of this tubercle, believed it to be remnant of the pointed ear of lower 
vertebrates. Deformities of the ear, unlike many other deformities of 
the head, are always seen at birth, although perhaps not so prominently 
as later in life. Not infrequently, the ear is found located forward, again 
backward, high or low upon the head. The two ears vary in position in 
the same individual, one ear often higher and placed more forward than 
the other. The ears of the negro are frequently arrested in development 



A STUDY IN DEGENERATIVE EVOLUTION 



143 



and are often deformed. Occasionally one ear will be markedly deformed 
while the other is normal in development. 





Figure 74 
Elephantine ear (original) . This shows 
arrest of development of the ear in 
phylogeny. 



Figure 75 
The Darwinian ear 
(Darwin). 



Supernumerary Mammae and Nipples. Supernumerary mammary 
glands and nipples are not uncommon in man as well as among the lower 
animals. They may appear on the chest, abdomen, axilla, arm, shoulder, 
cheek, buttock, leg and other parts of the body. Cases of ten have been 
observed. Annie Boleyn, the wife of Henry VIII, is reported to have 
had six toes, six fingers and three breasts. In the Louvre, in Paris, may 
be seen a picture, by Rubens, of a woman with four breasts. Leichtenstern 
has collected seventy cases in females and twenty-two in males of super- 
numerary breasts and nipples and believes that the accessory breasts or 
nipples are arrests in phylogeny. He says that the more remote, inferiorly 
organized ancestors had many breasts but that by constantly bearing one 
child, human females have gradually reduced the number to two. 

Investigators report a man with six distinct nipples arranged as 
regularly as those of a bitch or sow. The two lower were quite small. 
This man's body was covered with heavy, long hair, making him very 
conspicuous when seen naked during bathing. The hair was absent for a 
space of nearly an inch about the nipples. 

Many cases are on record where lower vertebrates have supernumerary 
breasts, located in different parts of the body like the human. Bland 
Sutton has shown that lemurs and monkeys have supernumerary glands 
in different parts of the body like those of the human. It would seem, there- 
fore, that supernumerary mammae and nipples, in the human, were arrests 
in phylogeny at the lower vertebrate period of development, hence atavistic. 



144 DEVELOPMENTAL PATHOLOGY 

Milk is not infrequently formed and children nourished from these super- 
numerary mammae. 

Uro-Genital Cleft. It is not uncommon to find degenerates (whose 
parents were relatives before marriage or who possess markedly exhausted 
reproductive organs) without an anus and with an opening from the rectum 
into the vagina and bladder. Sometimes both external genitals and anus 
are wanting. This phenomenon is easily explained in the formation of 
the uro-genital tract. Before the second fetal month, the alimentary 
canal and the spinal cord of all vertebrates arise from a common origin. 
At this period, the primitive gut tube becomes enlarged in the locality of 
the allantois &> form a common space, the cloaca. The hind gut, the 
allantois, Wolffian ducts and the post anal gut extend into this opening. 

The entoblast and ectoblast membranes form a delicate partition 
separating the ventral wall of the cloaca, dividing it into a posterior portion 
which forms the lower part of the rectum; the anterior is continuous with 
the allantois and receives the uro-genital ducts. It is this partition which 
is sometimes arrested in development which leaves an opening into the 
bladder and vagina, the fecal matter thus passing into the bladder and 
vagina, Fig. 76. 




Figure 76 
Anus is absent; rectum ends in the vagina (Ball). 

In birds, reptiles and monotremes, this opening is constant. The 
occurrence of the opening in man, therefore, is an arrest in phylogeny at 
the sauropsidian stage of development. The lower bowel may be deficient 
as far up as the superior third of the sacrum. When this is the case, a 
surgical operation is almost impossible. In a child who lived nine days, 
the sigmoid flexure of the colon terminated at the end of the bladder, Fig. 77. 

In a case reported by W. C. Bullard, when the girl was born it was 
discovered that there was no anal orifice and she was given up to die by 
the physicians. After a few days straining, a small amount of meconium 
escaped from the vulvar orifice. This increased in quantity and she began 
to thrive, but had great trouble with her bowels until 1888. For the past 



A STUDY IN DEGENERATIVE EVOLUTION 145 

few years, she has not been troubled beyond the fact that when the bowels 
are loose she cannot control the movements well, hence she sometimes 
soils her linen. When the bowels are not loose she has no trouble, 




Figure 77 
Anus is absent; rectum ends in bladder (Ball). 

but must go to stool on rather "short notice." For a few months 
(August, 1908), at irregular intervals, she experienced vague pains in 
her back and abdomen, which she thought were caused by menstruation. 

Examination revealed, extending from the fourchette posteriorly for 
about two centimeters and about one centimeter in breadth, a band of 
delicate skin, very closely allied to mucous membrane. From this back 
to the tip of the coccyx, the appearance was that of a normal perineum, 
the skin containing the usual .amount of pigment, but no signs of an effort 
at the formation of an anus. The ostium vaginae, to the finger, seemed at 
first quite normal but after the finger had penetrated about three centi- 
meters, it came in contact with an annular constriction which was evidently 
the internal sphincter of the rectum. When told to contract the sphincter, 
its grasp was quite perceptible, but had nothing like the force of the normal 
muscle. Just beyond this the finger came in contact with well-moulded 
feces and quite a roomy rectum. Bi-manual palpitation disclosed a narrow 
band running from one side of the pelvis to the other. On the left side, 
a quite movable body could be felt, which appeared about half the size 
of a normal ovary. This is undoubtedly a rudimentary ovary, as pressure 
on it causes that peculiar sensation complained of when the normal ovary 
is pressed. On the right side, occupying the same relative position, was 
a small firm body about one centimeter in diameter. This was, no doubt, 
the rudimentary right ovary. There was no evidence of a uterus, except 
the narrow band which crosses the pelvis, corresponding to the upper 
border of the broad ligament. The bladder was normal in every respect 
and a small speculum introduced showed the mucous membrane to resemble 
that of the rectum. 

Cloacal but ovaro-uterine perfect women are so common that the 



146 DEVELOPMENTAL PATHOLOGY 

question of delivery is not an infrequent obstetric problem. The cloaca 1 
state is here essentially sauropsidian. 

Excessive and Arrested Development of the Uterus and 
Ovaries. Occasionally, absence of the uterus and ovaries and fallopian 
tubes are reported. Sections of female subjects in whom the internal 
reproductive organs are wanting have been observed. In one case, the 
uterus and vagina were absent; in another, the uterus and vagina were 
absent and the kidney and bladder were deformed. Double uteri are 
occasionally reported with a single ovary and a fallopian tube for each. 
Pig. 78 shows arrest of development of the uterus and follicles with normally 




Figure 78 
Arrest of development of the uterus (Ziegler). 

developed ovary. All the marsupial and lower types are found sometimes 
in women, also showing an arrest in phylogeny. 

Non-Descent of the Testicles or Cryptorchidism. According to 
C. Moullin, normal descent of the testicle occurs in the eighth or ninth 
month of fetal life, the left one first, the right shortly before birth. In 
some animals, it is the same. In highly organized mammalia, the testes 
never come down at all. In the majority, they do not come down until 
the period of sexual maturity is approaching. In many, they come down 
only during the period of sexual activity. For the greater part of the year, 
they remain in 'the abdomen, and are comparatively insignificant in size. 
With each recurring sexual period, they increase enormously in bulk and 
descend into the scrotum for the time. At the end of the period, they go 
back into the abdomen and resume their former size and quiescent state. 
Here descent of the testes, increase in size and assumption of the functional 
activity are simultaneous events regulated by the same cause. In man, 



A STUDY IN DEGENERATIVE EVOLUTION 147 

the same three events occur as in these animals, but not as a rule, simultan- 
eously. The testes descend before birth, while still retaining infantile 
proportions. Increase in size and assumption of functional activity take 
place later. The origin of this difference is to be found in the assumption 
of the erect attitude and the consequent necessity for early closure of the 
inguinal canal. Clearly it would not be for the advantage of the race 
were the tunica vaginalis to remain widely open, leading vertically down 
from the bottom of the abdominal cavity, until sexual maturity had been 
attained. A tendency to the same condition occurs among the old world 
apes. The events are the same only the time relations are altered. Every 
now and then an exception occurs. Occasionally in man, one or both 
testes remain in the abdomen and do not of their own accord descend into 
the scrotum. The retention in the inguinal canal interferes frequently 
with the internal secretion function of the testicle so that the child's 
mental and physical growth is, as Kiernan points out, arrested. The 
replacement of the testicle in the scrotum, as A. E. Halstead has shown, 
by an operation will stimulate mental and physical growth as much as 
thyroid feeding does in the cretin. All these conditions found in man 
are arrests in phylogeny. 

Degeneration of the Bowels. Variations in size in development 
of the intestines at birth is not uncommon. They may be developed to 
the extent that they are a solid cord or may be distended so lightly as to be 
incapable of functioning or they may become excessively developed. Fig. 
79 shows the degenerate small intestine of a new born child, (a) greatly 




Figure 79 
Arrest of development of the intestine (Ziegler) . 



distended portion, (b, c, d, e) showing arrest of development, (f) normally 
developed portion. These are arrests in ontogeny. 

Spina Bifida. One of the striking conditions of degeneracy or arrest 
of development, is that in which the development of the bones enclosing 



148 



DEVELOPMENTAL PATHOLOGY 



the spinal cord is checked. The spinal cord is at first essentially a noto- 
chord, as in the lowest types of vertebrates. The structures surrounding 
the cord are not divided into vertebrae. This condition is permanent in 
the lancelet. Around the notochord is later formed a species of membrane 
which protects it, called the perichord. This condition is the second stage 
of development of the cord and is the permanent condition in the lampreys. 
Later still the cartilaginous vertebrae develop, and then these ossify at 
the point in the perichord which is to form a vertebra, from which bows of 
dense tissue unite behind. In front, similar bows form to constitute the 
bodies of the vertebrae. These bows remain ununited in some of the lower 
fish and at certain stages in the human embryo. As degeneracy checks 
the union of the bows of the vetebrae, imperfection and even absence of 
the union occurs, which constitutes the condition known as spina bifida 
(Fig. 80). This condition when complete is rarely compatible with life. 




Figure 80 
Spina-bifida (W. A. Pusey). 



In a partial state it is often found among degenerates and is an arrest in 
ontogeny. The seat of the trouble is frequently covered by an excessive 
development of hair (hypertrichosis), especially in the small of the back; 
this, which occurs very frequently in degenerates, resembles the tail which 
the ancients represented as that of the fauns (Fig. 81), and is an arrest in 
phylogeny. 

Deformity of the Hip Joint. A marked degeneracy sometimes seen 
in a child is that in which the head of the femur has not its proper relation 
in the acetabulum at birth. When man walked upon all fours, the body 
was supported by four instead of two legs. The weight of the body was 



A STUDY IN DEGENERATIVE EVOLUTION 149 

thus distributed. In his upright position, the bones of the leg and the 
thigh of man are much heavier and more sensitive than in the ape. The 
thigh bone or femur is the largest and heaviest in the entire skeleton and 




Figure 81 
Caudal appendix observed in a child (Clinic of M. Gosselin, Gould and Pyle). 

twice the size of the same bone in lower animals. The head of the femur 
articulates with the pelvis bone in a cavity called the acetabulum. The 
acetabulum is made up of three bones ; the ilium, the ischium and the pubis. 
The shape of the rim of the cavity is not unlike that of a horseshoe; the 
two ends pointing downward whether the animal be on all fours or in an 
upright position. When the animal is on all fours the middle of the horse- 
shoe is divided between the ischium and ilium. When in an upright 
position the middle of the horseshoe is entirely in the ilium, the rim having 
changed its position, thus giving support to the weight of the body. Occa- 
sionally, the rim of this cavity becomes arrested in its phylogeny (Fig. 82), 
at the anthropoid ape period leaving the cavity without support to the 
femur. 

Club Foot and Hand. Among expressions of degeneracy, often- 
times secondary, however, are club foot and hand. In this deformity, 
the sole turns inwards and upwards with the heel raised. 

In many instances, these retentions of positions are assumed by the 
limbs of the fetus in the course of evolution and therefore, are, in the adult, 
expressions of degeneracy. It is an interesting fact that club foot is 
normal in the apes. Every child's foot must pass through this ape phase 
and if it ceases to develop at this stage it must be considered that the 
child retains its ape-like characteristics, and hence is an arrest in phylogeny. 

Club foot was an expression of degeneracy in Byron, the poet, as 
Kiernan has shown. Commenting on this condition as found in Byron, 
F. S. Coolidge, remarks that "Byron undoubtedly suffered from double 



150 



DEVELOPMENTAL PATHOLOGY 



congenital club foot, the deformity being worse on the right." While in 
Coolidge's opinion congenital club foot unquestionably arises from 
different causes, it is, however, so frequently an accompanient of severe 




Figure 82 
Arrest of the rim of the acetabulum (Ziegler). A, old acetabulum without rim. 

articular cavity. 



B, new 



forms of mal-development and of congenital brain defects, that there can 
be no doubt but that imperfect constitutional development is one of its 
causes. That the deformity, with the many limitations which it involves, 
may tend to create morbidness is very likely to be an additional symptom 
of degeneracy which, in certain cases, is the underlying cause of the deformi- 
ty. Dareste, who has studied the club foot and hand from the standpoint of 
experimental teratology, finds that in no small number of cases club foot 
and hand result from checked development at the ape stage. 

Flat Foot. Since the immediate lower vertebrates walk on four 
feet, the weight of the body is thus distributed. In man's upright position, 
the entire weight of the body is centered on his two feet. To prevent jar 
to the body, the foot is formed into an arch. The plantar muscles, fasciae 
and ligaments, especially the inferior calcaneo-scaphoid, assist, together 
with the bones of the foot, to form this arch. The weight, therefore, 
comes upon the calcaneum forming the heel and the bones of the toe. 



A STUDY IN DEGENERATIVE EVOLUTION 



151 



From the flat foot of the anthropoid ape and lower negro type, as we 
ascend in the evolution of man, it becomes more arched (Fig. 83). When, 
therefore, man is flat-footed, it is an arrest at the anthropoid ape stage. 

It is a marked stigmata of degeneracy and is associated with grave 
moral defects and intellectual distortions. It is frequently found among 
paranoiacs, moral imbeciles, prostitutes, and "smart" business men. 




Figure 83 
Flat foot (original). This illustration shows the evolution of the foot from the anthropoid 

ape and lower negro type. 



Obesity. Obesity or lipomatosis is a nutritive expression of degener- 
acy especially noticeable in the second dentition, at puberty, and some- 
times at the climacteric. As Fere has shown, lipomatosis is an expression 
of stress at the period of evolution. Youthful obesity occurs in descendants 
of degenerates. In my experience, it is attended by great liability to 
disease and systemic weakness when under morbid influence. These 
lipomatosic children are liable to rheumatism (more properly gout) and 
hemorrhage from slight causes. Youthful obesity is sometimes, as Fere 
remarks, associated with precocious maturity and resultant early senescence, 
but more often with extended infantilism, as in the case of Dickens' "fat 
boy." 

Obesity, when associated with the acid states, is often the result of 
school strain. The apparent improvement shown in increased weight 
leads to increased strain, and many of these fat victims of school over- 
pressure enter insane hospitals at puberty as lunatics. 

Historic archives inform us that in some countries, it is considered a 
beautiful female adornment to be a shapeless mass of fat. From the same 



152 DEVELOPMENTAL PATHOLOGY 

authority we learn that Moorish women become very fat upon a diet of 
dates and a certain kind of meal. 

Kiernan has shown that while fat is but an expression of the imperfect 
burning up of energy food, it is frequently associated with genius from 
the irregular life-producing suboxidation in the acquired cases and the effects 
of strain at the periods of stress in defectives. It is often found, therefore, 
where degeneracy co-exists with genius. One of the signs of the depth of 
degeneracy in the maternal side of Byron 's family appears in the premature 
obesity of his mother, which same stigmata was apparent in Byron himself 
which worked, together with club foot, for Byron's discomfort. Victor 
Hugo, Theophile Gautier, Rossini, Jules Janin, Alexander Dumas, Balzac, 
and many others are in this category. 

That the lower animals pass through many changes in their evolution 
and that arrests in phylogeny occur in the higher species, the following 
case will demonstrate. The primitive horse (Eohippus) of North America, 
which was the size of a fox, possessed four well developed fingers and a 
rudimentary fifth, the thumb; in the two next higher animals (Orohippus 
and Epihippus), the size of sheep, the thumb bones have disappeared, the 
four remaining fingers persisting; in the next higher (Mesohippus) , only 
three fingers are well formed the fourth merely exists as rudimentary; in 
the Michippus, it has become still smaller; in the Portohippus of the Plio- 
dene, the fourth finger has entirely disappeared and three only persist. 
This animal corresponds to the European Hipparion and is about the size 
of the ass. Another Pliocene form still higher in the scale of evolution 
is the Pliohippus with the second and fourth fingers extremely rudimentary, 
the third much more highly developed. The modern horse has the third 
fingers largely developed and specialized, the second and fourth being 
very rudimentary. This aptly illustrates the law of economy of growth 
whereby an organ or structure is lost for the benefit of the organism as a 
whole. 

It was my good fortune to observe a horse in the streets of Chicago 
with four well developed supernumerary hoofs, located on the inner side 
of each leg. An arrest in phylogeny at the early Eocene period of horse 
development. This animal was a degenerate beast in every respect. The 
animal has sacrificed material needed for other purposes for the benefit of 
the hoofs. 

Summary 

Degeneracies due to increased check action involve: (1) structures 
in the evolutional stage prevailing at the time of stress, (2) vestigial rudi- 
mentary structures, and (3) transient structures. 



A STUDY IN DEGENERATIVE EVOLUTION 153 

A degenerate is an individual whose development reverts to less com- 
plex types, due to an unstable nervous system. 

An unstable nervous system is one in which the co-ordinating influence 
of the higher centers is either arrested or over-developed, in relation to 
the normal state of balance. 

Arrest or over-development of a part at the expense of the whole 
constitutes degeneracy. 

This unbalance may occur as between the nervous system and the 
body as wholes, either gaining at the expense of the other. 

Strictly speaking, every individual is a degenerate, the condition of 
absolutely normal balance being an ideal one. Just what degree of un- 
balance constitutes clinical degeneracy is a mooted point. 

Arrests and over-development of normal organs occur at periods of 
intra- and extra-uterine stress. The expressions of such degeneracy will 
be influenced by the original and succeeding periods of stress. They are 
generally divisible into mental and physical stigmata. 

Degeneracy due to arrest or over-development involves more than 
the simple retracing of the steps of normal evolution; a new factor enters 
into the equation in the impetus given to nutrition toward and away from 
the over developed and arrested organ respectively. 

Arrest of development manifests itself in abnormalities corresponding 
to the evolutional type prevailing at the time of arrest, and these may 
assume one of the following forms: (a) Structures normal in lower types 
may remain in rudimentary condition, (b) Structures which are normally 
transformed may retain their embryonic form, (c) Structures which normal- 
ly disappear may persist. 

The systemic unbalance which gave rise to arrest may in later life 
right itself, and the degeneracy to all practical intents be remedied; or it 
may persist and manifest itself in various directions at periods of stress; 
depending upon the profundity with which the organism is affected. 

The most prominent forms of degeneracy due to arrest of normal 
structures in man are as follows: 

Those affecting the bone development of the skull (durencephaly) . 

Those affecting the bone development of the body as a whole. 

Those affecting the brain and neurons. 

Anomalies of the hair. 

Gill clefts and defective ears (exceedingly common). 

Supernumerary organs (mammae and nipples). 

Infantile or undeveloped internal organs. 

Non-descent of testicles (cryptorchidism). 

Degeneration of the bowels. 

Spina bifida. 



154 DEVELOPMENTAL PATHOLOGY 

Deformity of the hip joint. 

Club foot and hand. 

Flat foot. 

Obesity and many others not enumerated here. 

Since all these degeneracies are, as already explained, most often 
brought about through disturbances of the central co-ordinating nervous 
system, they are frequently found associated with mental and psychic 
abnormalities. Sometimes the expense is on one side and sometimes on 
the other, so that with these deformities one sometimes finds deficient and 
sometimes excessive brain development. 






Chapter XIII 

CONSTITUTIONAL DEGENERACIES DUE TO DECREASED 

CHECK ACTION 

Of Structures that have passed in man's present evolution 

STRUCTURES which have become useless during the evolution of 
man that Shute calls "useless scaffolding left in the body" are the 
ear muscles, tail, tail muscles, great toe muscles, grasping power of 
infants, pineal eye and gland, cervical and short ribs and vermiform appendix. 

Ear Muscles. The three muscles of the ear are the attrahens, 
retrahens and attollens auren. These muscles, in the vertebrates, move 
the ears in different directions to detect sounds, while the animals are 
eating, without moving the head. Man, in his upright position, uses all 
his senses. He, therefore, moves the head in order to hear as well as see. 
Disuse, therefore, has arrested these muscles in development. Occasion- 
ally, these muscle arrests in phylogeny become potential at periods of 
stress and man by training them can move the ears. 

Tail and Tail Muscles. The tail, a very variable organ in biology, 
appears only to disappear in the higher Crustacea (crabs). It likewise 
appears only to disappear in the higher ichthyopsidae (frogs and toads). 

Virchow, discussing the presence of the tail in man (Fig. 81), points 
out that sacral trichosis (hairiness) is related to this condition. Sacral 
trichoses, represented by a tuft of hair, is all that is found in the anthropoids. 
Virchow found, in such tails as he was able to examine, no vertebral ele- 
ments, but merely a central canal representing the chorda dorsalis. Em- 
bryologists have found nothing but the chorda and atrophied medullary 
tube in the caudal appendage which is present in all human embryos at a 
certain period of life. 

A family in which the tail appeared for generations was reported in 
1888 by a Russian ethnologist, fulfilling Virchow's prophecy, made in 
1880, that such conditions would be found among the lower Mongolic and 
Negroid races. 

A certain Wesleyan missionary, George Brown, in 1876, spoke of a 
formal breeding of a tailed race in Kali, off the coast of New Britain. Tail- 
less children were slain at once, as they would be exposed to public ridicule. 
The tailed men of Borneo are people afflicted with hereditary malformation 
analogous to sexdigitism. A tailed race of princes have ruled Rajoopootana 
and are fond of their ancestral mark. 

The bone immediately below the sacrum, called the coccyx, is the 
essential representative of the tail in man. At a certain stage of human 

155 



156 DEVELOPMENTAL PATHOLOGY 

development, as in the tadpole, the tail disappears, the nine vertebrae 
forming the coccyx unite together and become a very diminutive bone 
which loses nearly all vertebral characteristics. Sometimes this bone 
retains its embryonic peculiarities to such an extent that in some degenerates 
it is a rudimentary tail. There are races in which, as Virchow points out, 
the tail has a tendency to appear more frequently than in others. Some- 
times children are born tailed. 

This condition has been found to occur with comparative frequency 
among the negritoes. In this respect, these people are below the anthro- 
poid apes, in whom the tail, considered from the tail standpoint, has 
degenerated, as in man, for the benefit of the organism as a whole. 

The tail muscles, still found in the human embryo, have become bands 
of fibrous tissue. They are occasionally discovered, fully developed, in 
the dissecting room, an arrest in phylogeny. 

Great Toe Muscles. In man's evolutionary flight, he falls more 
and more away from his ape-like conditions. This is especially noticeable 
in the differentiated use of the hands and feet, which in the apes are used 
alike for grasping and locomotion. In some respects this tendency is 
lacking in certain races, who use the foot for rowing. 

In man, the muscles which enable the apes to oppose the great toe 
with the others, or the Opponens Hallucis, are entirely wanting. Man, 
in his evolution, uses the feet more for locomotion and less for grasping. 
Therefore, when man arrives at his highest type we find this muscle has 
entirely disappeared through disuse, under the law of economy of growth. 

Grasping Power of Infants. Under the influence of deficient 
check action in ontogeny, not only are organs and structures retained, 
but potentialities occur in infants which indicate a persistence of the 
tendencies of the early race. When man lived in trees, he had a highly 
developed grasping power of the arm for clinging. 

Dr. Louis Robinson "tested a large number of new born infants in 
reference to this power by extending his finger or a cane, to imitate the 
branch of a tree and observed how long they would hang there without 
support (Fig. 84). He made experiments on about sixty children under a 
month old. About thirty of the children were not over an hour old. All 
but two were able to hang to the finger or cane by the hands, like an acrobat 
from a horizontal bar, and sustain the whole weight of the body for at least 
ten seconds. Twelve, less than an hour old, held on for half a minute, 
before the grasp relaxed. Four held on for one minute. Over fifty of the 
infants four days old could grip half a minute. Three weeks after birth 
the power of holding reached its maximum. At this age several hung for 
a minute and a half; two held for over two minutes; and one over two 
minutes and a half. One less than an hour old hung by both hands to 



A STUDY IN DEGENERATIVE EVOLUTION 157 

Dr. Robinson's finger for ten seconds. It then deliberately let go with 
the right hand, as if to seek a better hold, and continued its grasp with the 
left hand for five seconds longer. In none of these experiments did the 




Figure 84 
Illustrating the grasping power of infants (photographed by Dr. Louis Robinson) . (Shute) . 
Two infants ten and thirteen days old respectively, supporting their weight by the 
hands. 

limbs hang down in the attitude of the erect position. The thighs were 
invariably in the baby-monkey attitude, at right angles to the body. This 
attitude and the disproportionately large development of the arms com- 
pared with the legs give the photographs of the infants a striking resem- 
blance to the celebrated chimpanzee, Sally, of the London Zoological Gar- 
den. The infants very seldom gave any sign of distress and uttered no cry 
until the grasp began to give way. The fact that the flexor muscles of the 
forearm of a new born infant show such remarkable strength while the 
other parts of the muscular system are so conspicuously weak and flaccid 
— that they are able to perform a feat of muscular strength that will tax 
the powers of many a healthy adult — can be explained only on the theory 
of inherited potentiality from simian ancestors which lived in trees. This 
is no longer useful but is a vestigial potentiality, a useless scaffolding in its 
life history." 

The Pineal Eye and Gland. Perhaps the most striking instance 
of the sacrifice of an organ in local degeneracy for the benefit of the body 
as a whole is the pineal eye and body. In the remote ancestors of the 



158 DEVELOPMENTAL PATHOLOGY 

vertebrates, the acidian, the amphioxus, the slow worm, some lizards and 
the horned toad, there is a single eye in the center of the forehead (Fig. 85). 




Figure 85 
Head of a lizard or horned toad (W. S. Atkinson). Showing translucent pearly scale 

covering the pineal eye. 

In several lizards and other reptiles, its position is indicated by a trans- 
parent area in one of the plates of the head and by an opening in the bones 
of the roof of the skull. In young reptiles and especially in a New Zealand 
lizard (hatteria), its identity with an eye is decidedly evident. Lens, 
retina, pigment, cornea are present (seen microscopically) as in some 
snails, but they finally degenerate more or less as the animal reaches 
maturity. 

In the lizard, the pineal eye passes through the following stages of 
development: Formation of a hollow outgrowth from the roof of the 
third ventricle of the brain. This little sac elongates, changes its direction 
and becomes divided into a proximal and distal portion. The cells lining 
the distal part farthest from the brain become differentiated into the cell 
which will form the lens, and the cells which will form the retina. The 
distal parts become specialized; the lens, the retina and the stalk of the 
optic nerve are mapped out. The lens, the retina, and the optic nerve 
become fully formed. At this stage, the third eye has reached its limit of 
development. There is a well formed retina connected with the brain by 
a special optic nerve. The organ projects strongly from the surface of 
the head, but from this point, owing to the development of the cerebral 
hemispheres, degeneration begins. The nerve becomes broken and fatty, 
and pigmentary degeneration occurs in it. At the same time, the pineal 
eye having become useless or even harmful to the animal possessed of it, 
before the power of receiving perceptions of light has been lost and before 
the organ has been far reduced by the phylogenetic destruction, a veil of 
black pigment is formed over it, shutting it off from outer light. The 
nerve disappears completely before birth, its degenerate cells becoming 
lost in the mesoblastic skeletal tissue of that region. At the time of birth, 



A STUDY IN DEGENERATIVE EVOLUTION 



159 



the whole eye is enclosed in a thick membrane which isolates it. The 
deposition of pigment has destroyed any functional activity in the lens 
and the retina, but these parts none the less retain traces of a complicated 
structure recalling their condition when functional. 

In all vertebrates, including man, occurs a peculiar organ known as 
the pineal gland or eye. This pineal body was originally a central eye. 
The pineal body and its function have been mysteries to anatomists for 
years. In Addison's day as now among the theosophists, it was regarded 
as the seat of the soul. It is now known to be the remnant of an organ of 
sight, a third eye which looked out through the roof of the skull. The 
process of degeneration is clearly illustrated in Fig. 86. In the cy clops, 



B 



* ,r 



c ,r 




Figure 86 
Diagram indicating the progressive evolution and the degeneration of the pineal eye (Bald- 
win Spencer). A, perfect pineal eye, as found in the slow worm before birth or in the 
adult sphenodon (Hatteria); c, lens; r, retina; n, optic nerve; d, divertialum of the 
thalamencephalon. B, pineal eye in the first stage of degeneration as it exists in the 
Chamaeleo and as it was in the slow worm before stage A, The lens (c) and the retina 
(r) are not differentiated. C, Pineal eye in the degenerate form fpund in Calotes and 
Lelodera; C, lens; r, retina; n, optic nerve in fatty degeneration. D, very degenerate 
pineal eye, as in Cyclodus and like the earliest stage in the slow worm; there is no 
differentiation of the divertialum from the thalamencephalon. E, F, G, other modes 
of degeneration of the pineal eye. The eye lies within the skull and there is no parietal 
foramen; or, cranial membranes. E, ceratophora. F, birds; G, mammals. 



160 



DEVELOPMENTAL PATHOLOGY 



the state of things is reversed. The median eye, which ordinarily becomes 
the pineal body, here develops at the expense of the two eyes and the 
general nervous system. 

The cyclops (Fig. 87) was born to a seventeen-year-old neuropathic 




Figure 87 
Human cyclops (original). The pineal eye which has taken the place of the paired eyes is 
seen in the center of the forehead. This is an arrest at the reptilian stage. 

primipara, after a protracted labor. The child was living, but was killed 
by pressure on the funis. The mouth contained an ivory, tusk-like tooth 
at each corner. There was a mane-like hair around the neck. 

Cyclopia is often associated with the absence of both the internal and 
external ear, and with synotis (joined ears). 

In triophthalmic cases, the three eyes are usually separate, two occupy- 
ing the usual position, while the third is situated as illustrated in the case 
cited. Ninety families of degenerates, averaging eleven children each, 
had five cases of cyclops. 

Degeneracy, which affects so deeply the development of the eye, 
naturally tends to evince itself in other anomalous states in the organ. 
Excessive asymmetry of the body is one of the most noticeable of the 
stigmata of degeneracy. It is not astonishing to find that this asymmetry 
expresses itself both in the position as well as in the size and structure of 
the eye. Spiders and scorpions have a median eye spot associated with 
lateral eyes. 

Somewhere along the line of phylogeny (probably at the sauropsidian 
stage) , the pineal or central eye was lost for the benefit of the organism as 
a whole, while paired eyes took its place. In this connection, a marked 



A STUDY IN DEGENERATIVE EVOLUTION 161 

degeneracy or arrest in phylogeny is that of Fig. 88, the skull of a western 
desperado and murderer. The very large orbital cavities are an arrest in 
phylogeny at the lemurian stage and even lower carnivora type of mammal- 




FlGURE 88 

Skull showing excessive orbital cavities (Greves) . The large orbital cavities, the superciliary 
ridges, the large mastoid processes indicate reversionary tendencies to the lower savage 
type. 

ia. The large sockets are for the purpose of giving the eyes a wider range 
of vision. The large and prominent superior orbital arches are also a 
reversion to the anthropoid apes and early cave men for the purpose of 
protecting the eye from the sun, from limbs of trees and from blows of 
their enemies. The exceedingly large mastoid processes and occipital 
protuberances are also atavistic and are for the purpose of attachment of 
powerful muscles. With all these arrests in phylogeny, including a very 
small brain, such a person is more animal than human. 

Cervical and Short Ribs. In the embryo, man has been found to 
possess thirteen to fourteen pairs of ribs like the chimpanzee and gorilla. 
Adult man, however, has only twelve pairs. The "floating ribs" and their 
absence (in some instances) show this part of man's anatomy to be in a 
transitory state as these ribs are useless. 

One unpleasant and at times dangerous reversion encountered by 
surgeons is that of the cervical ribs long lost by most mammals but which 



162 



DEVELOPMENTAL PATHOLOGY 



return at the expense of the general organism to cause serious trouble and 
at times to endanger life. 

Vermiform Appendix. Among the structures of reversionary type 
that have attracted most attention of late years is the appendix vermi- 
formis. This, as elsewhere shown, is a rudimentary offshoot which is 
extremely variable. While this structure is very much in evidence, it is 
considered in this chapter because it is useless. Man retains this structure 
as a relic of having been at one time a vegetable feeder. In the koala 
(Australian native bear), a vegetable-feeding marsupial, it is more than 
thrice the size of the body. It is unusually large in the rabbit; in the 
horse, it has a caecum measuring on an average one meter in length and a 
capacity equal to thirty -five liters. In the carnivora, it has entirely 
vanished. In man, where it is sometimes absent and sometimes is as 
largely developed as in the orang, it is commonly from one half inch (Fig. 
89 a) to twelve inches in length (Fig. 90) and about a third of an inch in 





Figure 89 
The vermiform appendix (original). The vermiform 
appendix is seen at (a) only one-half inch in 
length. 



Figure 90 
The vermiform appendix (original). 
The vermiform appendix is six 
inches in length. 



diameter. The appendix is poorly supplied with blood, which predisposes 
it to attacks by microbes because of the absence of leucocytes to fight 
these and also because being, so to speak, a blind alley of the intestines, 
microbes find in it a suitable culture medium. The secretions of the 
appendix are very apt to decompose; hence a culture medium. 



A STUDY IN DEGENERATIVE EVOLUTION 163 

The extreme variability of this disappearing organ may be judged 
from the fact of their varying lengths, being anywhere from one half inch 
to eighteen inches. As it is best developed in degenerates, it constitutes 
in them one source of predisposition to death from blood poisoning or 
sudden shock. The location of this organ also tends to facilitate disease. 
In degenerates, it may be situated at any point upon the end of the big 
bowel, varying from two to three inches. This little bowel is worse than 
useless in man, being a source of serious danger. It is an instance of 
checked development of the same kind which causes the human liver to 
take on sauropsidian peculiarities. Man in this particular as well as the 
orang is lower than the carnivora, who have lost this worse than useless 
organ. Its tendency to disappearance in man indicates once more the 
truth that degeneracy of an organ is often, through the law of economy of 
growth, for the benefit of the organism as a whole. When the appendix 
is short, it is an advance in evolution; when long, it is an arrest in phylogeny. 

Summary 

There are many structures of the body which have become useless 
or have entirely disappeared. These structures are normal in adult lower 
vertebrates. They are as follows : — 

Ear muscles. 

Tail and tail muscles. 

Great toe muscles. 

Grasping power of infants. 

Pineal eye and gland. 

Cervical and short ribs. 

Vermiform appendix. 

Reversions to the lower vertebrate types have been reported many 
times by scientists and show an arrest in phylogeny. 

The loss of these structures has been for man's benefit as a whole. 



Chapter XIV 
CONSTITUTIONAL DEGENERACIES DUE TO CHECK ACTION 

Structures that are passing in Mans Present Evolution 



THE structures passing in man's evolution and which are most import- 
ant from a physiologic and pathologic viewpoint are the face, nose, 
jaws and teeth. In Chapter VII, "Development of Organs: The 
Head and Face," it was shown that the bones of the face, nose and jaws 
are partly derived from the skin and are dermal bones. A description of 
the phylogeny and ontogeny of these structures is there given. The degen- 
erate changes taking place in brain development and arrest of development 
of the face, nose and jaws, due to an unstable nervous system, may be 
accounted for, in part, to the dermal bones. Brain development depends 
on the expansive power of the secondary skull formed by the der- 
mal bones which may, in some instances, be degenerate, depending upon 
the early or late ossification of the sutures. 

Early or late union of the sutures of the skull depends, to a great extent, 
as has been shown, upon brain development. If the brain develop small 
in bulk, as in the microcephalic idiot, the sutures unite early and the result 
with the bones themselves, are usually very thick and heavy, because of 
bone excess. On the other hand, if the brain develop large in bulk, as in 
the macrocephalic idiot, these sutures unite late or may not at all. Dermal 
bones are frequently necessary to fill the spaces (a wise provision of nature) 
Fig. 34. Here the skull is very thin from want of sufficient bone to properly 
cover the brain. 

What is true of the cranium is likewise true of the bones of the face, 
jaws and teeth, since they are partly of dermal bones. The struggle for 
existence between the cranium and the bones of the face, jaws and teeth 
with the acquirement of normal nervous system is considerable, but when 
an unstable nervous system is to be reckoned with, the struggle between 
cranium on the one hand and the face, jaws and teeth on the other for 
bone material becomes fraught with difficulty. 

That under favorable conditions, a struggle for existence between 
the bones of the face, jaws and teeth should take place is to be expected, 
since the two halves of the fact develop independently of each other, and 
even each distinct bone has its own nerve supply. 

In this chapter, it is my purpose to classify and try to show how degen- 
eracies are brought about. 

164 



A STUDY IN DEGENERATIVE EVOLUTION 



1(5 



The Face 

The study of the law of economy of growth revealed a struggle for exist- 
ence between organs with interaction consequent on use and disuse of 
structures. Camper employed this law in his use of the ideal face of the 
Apollo Belvidere to illustrate the gradual retreat of the jaws from lower 
to higher types of. face (Fig. 91). 




Figure 91 
Evolution of the face from the anthropoid ape (Camper). Showing arrest of the face and 
development of the brain and skull. 

The Facial Angle of Camper, Cuvier, Cloquets, Jacquarts, the 
Munich-Frankfort Angle and that of Topinard involves merely the bones 
of the face, not the inferior maxilla. Most authors dealing with prognath- 
ism and orthognathism include merely the superior maxilla in the concept. 
Stomatologic specialists must include the inferior maxilla in the outline, 
in order to determine what may or may not be required in improving the 
jaws and teeth. In my studies of the etiology of irregularities of the jaws 
and teeth, I have simply extended the facial line downward below the lower 
jaw (Fig. 92). This skull is representative of the Apollo Bevedere. An 




Figure 92 
Face on the perpendicular line (original). This illustration shows the limit of the normal 
human face and jaws, in their evolution. 

imaginary perpendicular line, dropped from the superciliary ridge below 

the lower jaw, decided whether the jaws be prognathous or orthognathous. 

The Ideal Face of Camper (last figure) is a norm, which shows where, 

in most cases, anatomic progress ceases and pathologic begins. At one stage 



166 DEVELOPMENTAL PATHOLOGY 

in the evolution of man the eyes, face, nose, jaws and teeth were most 
essential in obtaining food, and equally so in sexual selection. 

It has been previously shown that when man proceeded to walk upon 
two legs instead of four and to use his hands for the purpose of feeding 
himself, the face and nose and long jaws were not required. 

Owing to disuse, these structures have atrophied (degenerated) . The 
brain and skull, on the other hand, needing this material, have appropriated 
it to their own uses. Wild animals, domesticated, show this change. The 
wild boar and domestic pig (Fig. 36) is one illustration; the bull dog another. 
This evolution in man is a normal healthy process. The structures of the 
face and nose develop partly from cartilage and partly from dermal bones. 
Calcification, therefore, does not go on uniformly in both structures. 
Cartilages are more susceptible to the influence of disease than dermal 
bones, because cartilages are slower in calcifying. They ossify slower than 
the dermal bones of the head. According to DeMoor, in their status as 
newer acquired structures, they are first to be affected by disease and to 
disappear. Changes in these structures take place along the line of least 
resistance, since the bones of the face and nose are the most variable in 
development. An unstable nervous system produces untoward effects 
upon these structures. Arrests in phytogeny and ontogeny, therefore, are 
to be expected. 

In the development of the bones of the head, the order is as follows: — 
the chondrocranium, the first stage; the dermal bone function to protect 
the brain, the second stage; the ossification of the primordial chondrocran- 
ium, the third stage; the ossification of face, nose and jaws, the fourth 
stage. 

As man developed, owing to brain increase, he acquired the power of 
obtaining and digesting food with less expenditure of physical strength. 
The jaws and teeth become less a factor in food getting, hence their disuse 
and atrophy. 

Up to this period of facial atrophy, the cavities of the nose were large 
enough for the purpose of breathing, the jaws large enough for the teeth, 
the teeth rarely decayed and interstitial gingivitis (owing to large, well- 
developed alveolar processes) seldom occurred. 

While healthy recession is still progressing under the law of economy 
of growth, the perpendicular line remains the dividing line between the 
normal and abnormal. 

Associated with antero-posterior arrest is lateral arrest of the face, 
which as a rule, is about as great as the antero-posterior. In such cases, 
protrusion (excessive development) of the nose and upper jaw often occurs. 
The lower jaw is usually arrested. The arrest begins at the upper border 
of the nasal bones at their junction with the frontal, extending downward 



A STUDY IN DEGENERATIVE EVOLUTION 



167 



to a point midway between the angle of the lower jaw and the symphysis of 
the chin. 

This phase of evolution underlies all pathology of the face, as well as 
of the nose, jaws, alveolar processes and teeth. The illustrations supple- 
menting those of Camper portray this reverse phase where symmetry of 
the body as a whole is sacrificed to changes in the nose, jaws, alveolar 
processes and teeth, in order to preserve cerebral gains. 

The accompanying illustration (Fig. 93) taken from photographs of 




6 < 7 
Figure 93 
Evolution and degeneration of the face (original) . The process of evolution of the human 
face is still going on. This illustration shows clearly the degeneration of the structure 
of the face for the benefit of the brain which is evolving higher in man's evolution. 



patients, accurately portrays arrests of the face for the benefit of the brain. 
The gradual recession of the face and the forward development of the 
brain is a gradual continuation of Fig. 91, in the line of evolution. From 
the relation of this face degeneration, nearly all diseases of the nose, jaws, 
alveolar processes and teeth result. In many cases, reverse evolution 
progresses still further, until owing to an unbalanced nervous system and 
free movements of the lower jaw, atavism intervenes. Illustrations 8 and 




Figure 94 

Phylogenic arrest of the face (original) . Here is 

seen an atavistic tendency in which the brain 

is undeveloped but the face, jaws and teeth 

are a return to the lower negro type of face. 




Figure 95 

Prognathous skull (Greves). Showing 

type of previous figure. 



168 



DEVELOPMENTAL PATHOLOGY 



9 (Fig. 93) exhibit a greater exaggeration of the lower jaw, that is, a return 
to the anthropoid and lower negro types. 

In the study of the evolution of the face, five types are to be considered : 
First: An Arrest of the Face and Head in its Phylogeny. Here 
the face extends beyond the perpendicular line (prognathism) and the 
forehead recedes inside the line and is atavistic (Fig. 94). The teeth articu- 
late normally. 

Fig. 95 is that of a skull showing more clearly the outline of this type 
of face. The jaws, face and nose are outside the perpendicular line. The 
forehead recedes inside the line. The jaws are large, well developed, with 
a width of two and one-fourth inches. The thirty-two teeth are large, well 
developed, with bell shaped crowns and with little or no decay. Tooth 





Figure 96 

Ontogenic antero posterior arrest of the face 

(original). 



Figure 97 
Skull showing ontogenic arrest of the face 
(Greves) . Skull showing type of previous 
figure. 



structure in both enamel and dentine is fine grained and dense. The teeth 
are well set in the jaws, with plenty of alveolar process between and about 
their roots, giving sufficient nourishment to the surrounding structure, 
with little tendency to interstitial gingivitis. The vault is medium in 
height without irregularities of the teeth. Such people masticate their 
food and use the jaws with much more vigor and pleasure than those who 
possess smaller jaws. Their jaws are atavistic and resemble the lower 
negro type. The mentality of this class varies from the lowest form of 
idiocy, with lemurian brain capacity, to the highest and most intelligent 
individuals. The forms of mentality have been discussed in Chapter IX. 
Second: The antero-posterior arrest in which the face is arrested in 



A STUDY IN DEGENERATIVE EVOLUTION 169 

its ontogeny inside of the perpendicular line, including the upper jaw. 
The lower jaw is normal or it may be arrested (Fig. 96). 

Fig. 97 is that of a skull which illustrates the type of face described on 
or inside the perpendicular line. The jaws, as a rule measure from 1 . 70 
to 2.25 inches across. There are rarely thirty-two teeth; one or all four 
of the third molars are wanting. There are nearly always irregularities 
of the teeth, decay-and interstitial gingivitis. Mastication of food is poor- 
ly performed. The mentality of this class varies from the lower to the 
highest brain development. The figures are graded according to mentality. 

Third: There is a lateral arrest in the ontogeny of the face, beginning 
at the nasal bones and extending downward and backward to a point 
midway between the symphysis and the angle of the jaw. There may be 
an arrest antero-posteriorly, or the face may extend beyond the perpendi- 
cular line. The lower jaw may be outside, on, or inside the line. The 
teeth may or may not be normal in occlusion (Fig. 98). 

Fig. 99 is a skull showing the type of face described in this classifica- 





FlGURE 99 

Figure 98 Skull showing type of previous figure 

Ontogenie lateral arrest of the face (original) . (Greves) . 

tion. The narrow, contracted bones of the face are well outlined. The 
jaws are always too small to contain thirty-two teeth, in normal position. 
If they be present, they are irregularly placed, or the third molars are 
unerupted. More frequently one or all of the third molars are absent. 
Not infrequently some of the other teeth are lacking. The alveolar pro- 
cesses are long and thin with marked interstitial gingivitis. Decay of the 
teeth is very common. 



170 



DEVELOPMENTAL PATHOLOGY 



Fourth: The face and upper jaw may become arrested in its phylo- 
geny and remain outside the perpendicular line, and the lower jaw remain 
on the line or arrested in its ontogeny inside the line. The teeth on the 
upper jaw protrude beyond the lower (Fig. 100). 

Fig. 101 shows the bones of the face in this class of deformities. There 
is always an excessively developed upper jaw with a normal or arrested 
lower jaw. In correcting such a deformity, it is very essential that the 
operator should satisfy himseh* in regard to the nature of this deformity 
before undertaking surgical procedure. Sometimes the body of the lower 
jaw is arrested in development and sometimes the rami. Again the lower 
jaw may be normal. 





Figure 100 
Phylogenic arrest of the face and upper jaw 
(Lee Wallace Dean). 



Figure 101 
Showing type of previous figure 

(Greves) . 



Fifth: The face and upper jaw may become arrested in ontogeny and 
remain inside the perpendicular line, while the lower jaw, on account of 
its mobility, may become arrested in its phylogeny, extending beyond 
the perpendicular line. The teeth upon the lower jaw protrude beyond 
the upper (Fig. 102). All other forms are modifications of these five. 
They may be more or less intense. 

Fig. 103 is a skull demonstrating this class of deformities. In this 
illustration, the body of the jaw has become over-developed. In other 
patients, the rami may be excessively developed and the body remain 
normal in size. 

This general consideration of changes in face development leads to 
discussion of individual degeneracies. Taking Fig. 91 as our guide y 



A STUDY IN DEGENERATIVE EVOLUTION 



171 



the struggle for existence between the brain on the one hand and the face 
on the other is most striking. A consideration of evolutionary changes in 
phylogeny reveals that development began without a brain and the head 
was on a line with the body, like fish and reptile, and was nearly all face 
and jaws; it is easily understood, then, the struggle that has taken place 
between the brain, face and jaws for supremacy through the ages. Many 
animal species with advanced brain development and smaller jaws have 





Figure 102 
Phylogenic arrest of the lower jaw 
(original) . 



Figure 103 
Skull showing type of previous figure 

(Greves) . 



strayed from the direct path of evolution, while man has persisted in the 
straight and narrow way until the brain has developed and has become 
master over the face. 

Under each type, there is as great a contrast in mental development 
as there is in face and jaw deformities. 

In this struggle for existence not infrequently, owing to disease in the 
parent or child, atavisms occur. The brain remains undeveloped at periods 
of stress and resembles pre- vertebrate types, like the cy clops (the cy clops 
have already been described and illustrated); vertebrate types like fish, 
reptile, bird, lower mammal, lemur and anthropoid ape. 

First Classification. 



Fig. 104 is the head of an idiot. The struggle here has been reversed; 
the face, jaws, teeth and ears have gained at the expense of the brain, 
resulting in a most marked atavism. The atavistic brain of this girl (Fig. 



172 



DEVELOPMENTAL PATHOLOGY 



58) is an arrest in phylogeny and at the lemurian stage. The cerebellum 
is exposed and the convolutions are few. The atavistic jaws are large as 




Head of an idiot girl (Ziegler). 



Figure 104 
Showing sacrifice of brain and skull for the benefit of the 
face, jaws and ears. 



well as the teeth, free from decay in normal people, but in such a patient, 
decay is very active due to an unstable nervous system and want of personal 
cleanliness. 

Fig. 105 illustrates the head of a knife-grinder (L'Arrotino) of Asia 
Minor, from a famous marble in the Uffizi Galleria, Florence. The idiotic 




Figure 105 
Head of a knife grinder (L'Arrotino). 



expression on the face is pronounced. He has a receding (atavistic) fore- 
head with protruding (atavistic) face and jaws. The fact that he has an 
occupation shows that he possesses a brain a little in advance of the idiot 
in the previous illustration. This man comes under the pauper class. 



A STUDY IN DEGENERATIVE EVOLUTION 



173 



Fig. 106 is that of a thirty-six-year-old habitual criminal. He is a 
horse thief. He has been in the penitentiary most of the time for twenty 
years. The jaws measure two and one-half inches in width and have 




Figure 106 
Habitual criminal, horsethief (original). 



thirty-two well developed sound teeth, 
than in the two preceding illustrations. 
Fig. 107 is that of a Russian harlot. 



The brain development is higher 
The anterior part of the head 







Figure 107 
Russian harlot (original) . 

slopes backward denoting lack of frontal brain development. The jaws 
protrude beyond the perpendicular line. The jaws have large well devel- 
oped teeth, without caries. 

Fig. 108 is that of a thirty-two-year-old university graduate who 
gained considerable notice as an athlete during his college career. Since 
graduation his highest ambition is a professional masseur. He has no 



174 



DEVELOPMENTAL PATHOLOGY 



office but goes to his patrons. His fees are exorbitant and he believes his 
services are worth more than he charges. Only a very few wealthy people 




Figure 108 
A college graduate, and extreme egotist (original). 

are his patrons. He spends all his money upon dress and borrows when 
occasion requires. His jaws are large and have thirty-two well developed 
teeth. He is an extreme egotist. 

Fig. 109 is that of a well-known actress. This head shows the extreme 
in mentality. The jaws protrude beyond the perpendicular line. 




Figure 109 

A brilliant actress (original). Although the type of head and face is similar to the class yet 

in this case the gray matter and cell development predominates. 



It will be seen that atavism in brain and jaws (Fig. 95) causes these 
structures to descend the scale of evolution (Fig. 91). The distance to 
which the individual may travel will depend upon the depth of the degen- 
eracy. 



A STUDY IN DEGENERATIVE EVOLUTION 



175 



Second Classification 

In the second classification, the face and jaws are on or inside the 
perpendicular line in normal healthy evolution. This, in a general way, 
is an advance in facial evolution, but, however, is not always the case, 
since neurasthenia, in parent or child or both, may cause arrest of develop- 
ment in brain and face ontogeny. 

Fig. 110 is that of an insane person. There is marked arrest of the 
face, including the eyes, which are small and sunken. The nose is markedly 






iW,*. " ' W ^1 


i 



Figure 110 
An insane person (original). 



Figure 111 
A one-sided genius (original). 



deformed and curved to the left. There is nasal stenosis with deflected 
septum; hypertrophy of middle turbinates on the left and arrested middle 
turbinates on the right side. The right eye and ear are higher than the 
left. There is an arrest of the upper jaw with a V dental arch and vault. 
Teeth are badly decayed. The lower jaw is normal. The brain of this 
man is not unlike that of Fig. 59, in which only a few convolutions are seen. 

Fig. Ill represents the face of a one-sided genius, a mechanic who has 
produced a number of useful inventions. His hobby is perpetual motion. 
There are times when he has complete loss of memory. On one of these 
occasions he demanded his salary from the wife of the owner of the shop 
in which he was employed. Because she refused, he struck her on the head. 
For this offense he was sent to the hospital for the criminal insane. The 
eyes are small and sunken. There is nasal stenosis with marked arrest of 
the face and upper jaw, and a partial V-shaped dental arch. The ears 
stand out from the head. The lower jaw is normal. 

Fig. 112 is a twenty-two-year-old man with lateral arrest of the nose, 
face and upper jaw. He has harelip and cleft palate. The right side of 
his face, including the eye and ear, is higher than the left. The nose is 



176 



DEVELOPMENTAL PATHOLOGY 



long and deflected to the right. The right ear is fairly normal while the 
left is badly deformed. The teeth are irregular. The lower jaw is normal. 





Figure 112 
A degenerate face but fairly well developed 
brain (original). 



Figure 113 
A kleptomaniac (original). 



The young man sold newspapers. He assaulted the man for whom he 
worked and was sent to the reformatory. 

Fig. 113 is a twenty -nine-year-old clegyman who gained considerable 
public attention from his sermons. He has a mania for visiting book stores 
and appropriating books for his own use without paying for them. There 
is marked arrest of the face, nose and both jaws. The right side of the 
face, eye and ear are higher than the left. The upper border of the left 
ear is arrested. He has a high vault with deformed dental arches. There 
is quite an arrest of the lower jaw. 





Figure 114 Figure 115 

A criminal banker (original). A brilliant lawyer (original). 

Fig. 114 is that of a forty-eight -year-old banker. He was sent to the 
penitentiary on an indeterminate sentence for swindling his patrons by 



A STUDY IN DEGENERATIVE EVOLUTION 



177 



selling first mortgages on the same piece of property nine times, and also 
for other similar crimes. Here there is marked arrest of the face, eyes, 
upper jaw, with normal lower jaw. This man formerly had adenoids, 
hypertrophied turbinates and deflected septum. He also has a V dental 
arch and high vault. The ears are large and stand out from the head. He 
is flat footed and toes in. 

Fig. 115 represents one of the brainest internaitonal lawyers. While 
the type of face is not unlike that of the others in this class, the brain 
development is similar to that of the great mathematician Gauss. 

Third Classification 

In the third classification, the arrest of development is a lateral arrest 
extending from the nasal bones, downward and backward, midway between 
the symphysis and the angle of the lower jaw. The face is narrow and is 
called a hatchet face. The nose is long and thin. The lower jaw is usually 
arrested in this class of cases. 

Fig. 116 is the face of an insane criminal. In this patient, the effects 
of neurasthenia in the parents or disease in the child has left its imprint 





Figure 116 
An insane criminal (original). 



Figure 117 
A ward politician, an habitual liar (original). 



most forcibly upon the brain and face. To the observing physician, there 
could be no mistake in locating excesses and arrests of development in face, 
eyes, nose, mouth, teeth and chin. We should expect to find irregularities 
of the dental arches, mouth-breathing, hypertrophied tonsils, adenoids, 
hypertrophy of the nasal bones, turbinates, vomer, with hypertrophy of 
the mucous membrane. The brain arrest might resemble any one of the 
illustrations shown in Chapter IX. 

Fig. 117 is that of a twenty-four-year-old man who not only has the 



178 



DEVELOPMENTAL PATHOLOGY 



lateral arrest of the face but has a very sloping forehead as well as arrest 
of the chin. He is a ward politician of a low order and an habitual liar. 
He has served time in the state reformatory. A description of the deform- 
ities of this face are not unlike those of the previous character. He has a 
marked saddle dental arch with high vault, nasal stenosis with the usual 
hypertrophies and atrophies. 

Fig. 118 is a thirty -five-year-old criminal. He has committed two 
murders, one in the west, the other in the east. There is a marked lateral 








Figure 118 
A murderer (original). 



Figure 119 
An actor (original). 



arrest of the face with deformed jaws and V dental arch. This subject 
has adenoids, a deflected septum with hypertrophied turbinates. The 
right side of the face, eye and ear are higher than the left. Eyes are small 
and sunken. 





Figure 120 
A "smart" business man (original). 



Figure 121 
An "eccentric" business man (original). 



Fig. 119 is the face of an English actor of no mean ability. He has 



A STUDY IN DEGENERATIVE EVOLUTION 



179 



the hatchet variety of face. He has marked dental irregularities and high 
vault. 

Fig. 120 is an illustration of a "smart" business man, a manufacturer. 
He has attained great wealth by taking advantage of people in business. 
He possesses the usual deformities of face, nose, jaws and teeth. 

Fig. 121 is the face of a thirty-two-year-old business man who is eccen- 
tric in a marked degree. He has an unusual lateral arrest of the face, the 
jaws measure one inch from the buccal surfaces of the first molars, a very 
pronounced saddle dental arch, high vault and irregular teeth. He has 
had his nose operated upon for adenoids, spurs and other hypertrophies. 

Fourth Classification 

In this class the deformities are quite prominent, the dental articula- 
tion is so poor that proper mastication is impossible. 

Fig. 122 is the picture of a forty-eight-year-old business man. He is 
only fairly intelligent. The shape of his head would indicate that. He 




Figure 122 
"Fairly intelligent" business man (original). 

is not over and above successful in his business. He has a large nose, ears 
and upper jaw, with a decided lateral arrest of the face and lower jaw. 
The teeth of the upper jaw extend beyond the lower . 60 of an inch. The 
usual hypertrophy of tonsils, adenoids and turbinates are noticed. This 
class of deformities is also seen in the different walks of life, but more 
especially is this the case in the more marked forms of degeneracy. We 



180 



DEVELOPMENTAL PATHOLOGY 



rarely find this type of face among the more intelligent class of people. 
So marked an impression is made upon the child by disease in the parents 
that the brain feels the impress. 

Fifth Classification 

Of all the facial degeneracies, none are so pronounced as those which 
come under this classification. From a pathologic viewpoint, it demon- 
strates most clearly the action of an unstable nervous system upon develop- 
ment of bony structures. 

In this class of cases there is marked ontogenetic arrest of the face 
nose and upper jaw, while there is excessive phylogenetic development of 
of the lower jaw. The upper jaw, being a fixed bone, does not receive as 
much nourishment as the lower jaw. The lower jaw being movable, it is 
more liable to become excessively developed at the expense of the upper 
jaw. 

Fig. 123 shows such a condition. The face, including the nose and 
upper jaw, has become arrested while the lower jaw is excessively developed. 




Figure 123 
A successful lawyer (original). 

In this patient, the lower teeth protrude .30 of an inch beyond the upper. 
I have in my practice a thirty-eight-year-old lawyer of no mean ability, a 
university graduate and also a graduate of a law school, with a similar 
facial and jaw deformity. 

Intellectual Relationships. A classification of facial types and 
their relation to intellectuality has been clearly shown. There is not nor 
can there be a criminal type of face as claimed by some scientists. All that 
can be said in this relation is there is a degenerate type of face. The 
mentality may vary from the lowest idiot to the most intellectual. Be- 
tween the two extremes all the views occur. These facial types may be 



A STUDY IN DEGENERATIVE EVOLUTION 181 

found in all nationalities. Each nationality has its peculiar type of face. 
All studies must be considered from the two standard forms of heads, the 
br achy cephalic of the German and the dolichocephalic of the negro. In 
the blending of nationalities and the intermixture of races, the tendency 
of these two extremes in mingling is to produce a mesaticephalic head. 
What would be considered normal in one nationality would be a degeneracy 
in another. In the study of degenerate facial types the normal native 
type must always be a norm from which to study departures. 

National Development. It is interesting to study some of the 
basic principles in two or three nationalities to note the progress of evolu- 
tion in the facial angle. To start with the negro type (Fig. 91) including 
all the heads in this figure and those of Fig. 93 we have the types of all the 
different races from the ancients to modern times. A close study of these 
illustrations reveals a firm foundation to determine racial types by the 
facial angle. A comparison of the two extremes, from the lowest American 
negro types to the highest educated people of the oldest countries of the 
world, may be of value. 

An examination of the lowest negro type in Mississippi was made by 
Dr. William Ernest Walker of New Orleans. His examinations of three 
hundred and fifty-seven, showed the facial angle protruded beyond the 
perpendicular line in ninety-seven and five tenths per cent of jaws, while 
two and five tenths per cent of jaws examined were on the line. An 
examination by Dr. Arthur R. Dray of six hundred and eighty-six negroes 
in Philadelphia, eighty-three and fifty-seven one hundredths were found 
outside the perpendicular line; fifteen and ninety-five one hundredths on 
the line and forty-two one hundredths inside the line. An examination 
of one thousand and eighty-five in Chicago, fifty-one and six one hundredths 
per cent protruded; thirty-one and eight tenths were on the line and sixteen 
and six tenths per cent were inside the line. An examination of one thous- 
and negroes in Boston by Dr. Eugene F. O'Neill showed forty-five and 
four tenths per cent outside the line; thirty-nine and five tenths per cent 
on the line and fifteen and one tenth per cent inside the line. It will be 
seen, therefore, that in Northern and in old negro families, from race 
admixture and environment, there is less protrusion and more recession 
than in the Southern pure negroes. Arrest of the bones of the face is as 
common in old negro families in the North as among the Caucasic races. 

An examination of ten thousand people in the streets of London on 
the other hand revealed the fact that in only four and thirteen one hun- 
dredths per cent of people examined did the jaws extend outside the per- 
pendicular line; twelve and eighty-seven one hundredths per cent on the 
line, and eighty-three per cent inside the line. In an examination of three 
thousand English school children (about ten years of age) ninety-three per 



182 DEVELOPMENTAL PATHOLOGY 

cent possessed jaws inside the perpendicular line; six per cent on the line 
and one per cent outside the line. An examination of eight thousand 
people in Boston showed six per cent of jaws extending beyond the per- 
pendicular line: fourteen per cent on the line and eighty per cent inside 
the line. 

In comparing the evolution of the Aryan race with those of the negro, 
it will be seen that the negro in this country has undergone, in two hundred 
and fifty years, as rapid facial change as has taken place in the Aryan 
races in thousands of years. This is interesting, since we can more readily 
understand the causes which produce these changes in the facial angle and 
study them in the negro race. 

Ancient and Modern Characteristics. In comparing the lateral 
measurements of the jaws (Fig. 155) of modern races with ancient skulls 
and ancient races, a marked difference in size is noticed. A few of these 
measurements will be given here for comparison. Examinations of ancient 
skulls made by the late Dr. Mummery, in 1860, of ancient British skulls 
measured minimum 2.12 inches, maximum 2.62 inches, with an average 
of 2 . 37 inches. The modern English jaws measure minimum 1 . 88 inches, 
maximum 2 . 44 inches, with an average of 2 . 19 inches. The jaws of people 
living in America measure minimum 1 . 75 inches, maximum 2 . 52 inches, 
with an average of 2.14 inches. The difference between the ancient 
Roman soldiers and modern Romans is the same as that of the English. 
The lateral measurements of the pure negro as found in Mississippi are 
minimum 2.25 inches, maximum 2.75 inches, with an average of 2.51 
inches. The lateral diameter of modern negroes varies considerably owing 
to neurasthenia in the parents and disease in the child. Some jaws measure 
as low as 1 . 75 inches. The jaws of modern negroes residing in Boston for 
many generations are not unlike those of the native whites. 

Dr. Charles Ward says a "point in which the jaws of aboriginal tribes, 
are, as a rule, superior to those of civilized races is in the proportions of the 
horizontal ramus. As pointed out by Harrison Allen, the alveolar and 
inferior border of the jaw tend to parallelism in savages, while in civilized 
races the symphysial height is usually greater than the height in the vicinity 
of the molars. This may be due to gradual degeneration of the platysma 
myoides muscle. Of the significance of the "antegonium" or "pregonium" 
of the same author I am uncertain, but incline to the belief that it is a 
" stigma of degeneration." Finally, an as yet incompleted study of the 
relative proportion of jaw to skull has convinced me that the jaws of savages 
are not only proportionately but actually heavier than our own, and that 
the " cranio-mandibular index," as I term it, which is the ratio between 
the weight of jaw and weight of cranium, rises steadily as we descend from 
semi-civilized to barbarous and savage tribes. 



A STUDY IN DEGENERATIVE EVOLUTION 183 

"Thus, while the white males examined gave an index (proportion of 
jaw to skull) of 11 .8, the male Australians presented an index of 15 .4. 

"Absolute size of the lower jaw is greater in savages: Of nine 
aborigines, including seven North American Indians, one African and one 
American negro, six Malays and five Australians, all with beautifully 
perfect teeth, the mean weight of the jaw was 102.4 grams. Of eighteen 
white males the. mean weight of the jaw was only 83.4 grams. Yet the 
weight of the skull was nearly alike in both classes, being 690 . 9 grams for 
the aborigines as against 680.5 for the whites. The weight of the lower 
jaw compared with that of the cranium, or the Cranio-Mandibular Index 
is 15 . 6 for aboriginal men as against 12 . 16 for white men. It is 46 . % for 
the anthropoid apes, our nearest living relatives among mammals. " 

The change in the two extremes of heads, the brachy cephalic and the 
dolichocephalic to the mesaticephalic also produces change in the shape of 
jaws in like manner. Instead of the large round jaw of the brachy cephalic 
and the long narrow jaw of the dolichocephalic, a medium size jaw develop- 
ment also follows. 

Summary 

In man's homogenetic course, the face, nose and jaws are growing 
smaller and the teeth are being lost through disuse of structures. 

In studying the facial angle, the lower jaw should be included in the 
concept. This is very necessary in the correction of irregularities of the 
teeth, since an imaginary line extending from the superciliary ridge below 
the lower jaw determines whether the jaws be protruding or not. Many 
noted scientists have lost sight of this and have made no mention of it in 
their writings. 

Owing to disuse, the facial structures are degenerating, while the 
brain and skull are increasing from the material which would ordinarily 
go to these structures. 

In the growth of the bones of the head, there is first, the chondrocran- 
ium or primary skull; second, the protection of the brain by the dermal 
bones; third, primary skull ossification; fourth, face, nose and jaw ossifica- 
tion. 

Before man began to obtain and digest his food with less physical 
exertion, the jaws were large enough to contain thirty -two well developed 
teeth with little decay and no interstitial gingivitis. 

At the present time, on account of arrest of the bones of the face and 
disuse, the jaws have grown smaller, are inside the perpendicular line and 
cannot contain thirty -two well developed teeth, decay is prevalent and 
interstitial gingivitis is common. These conditions are the foundation of 



184 DEVELOPMENTAL PATHOLOGY 

all pathology of the face, nose, alveolar process and teeth. In order to 
make this clearer, I have added to Camper's illustrations, profiles of 
patients, typifying facial atrophy for the brain's benefit. 

To obtain a clear idea of facial development, five types must be borne 
in mind. First, the protrusion of the jaws beyond the perpendicular line 
and recession of the forehead inside the line. Second, the recession of the 
jaws inside the perpendicular line. Third, lateral arrest of the face. 
Fourth, the face and upper jaw protrude beyond the perpendicular line 
while the lower jaw is inside the line. Fifth, the face and upper jaw 
remain inside the perpendicular line and the lower jaw protrudes beyond 
the line. 

Monstrosities sometimes occur resembling prevertebrates and verte- 
brates in connection with these face malformations, due to a lack of brain 
growth at periods of stress. The mental conditions as well as other deform- 
ities are discussed under each illustration. 

Many investigators claim there is a criminal type of face but a study 
of facial deformities precludes this statement. There is, however, what 
may be called a degenerate face. 

Brachycephaly, or round head, and dolichocephaly, or long head, 
are the two classifications from which to study head change. Owing to 
race intermixture, environment, change of climate, soil and food the 
tendency is toward mesaticephaly or medium head. The change in skull 
type has produced a similar change in the jaws. The greatest change in 
head and face type is to be found in the evolution of the American negro. 
According to Charles Ward, the lower jaw of savages is greater in size and 
weight than in civilized races. 



Chapter XV 
THE NOSE 

The External Nose — Arrests in Development in its Phytogeny 

THE external nose, in its phylogeny, passes from the snout stage of 
the lower vertebrates to the aquiline type of the genus nasalis 
(proboscis monkeys) (Fig. 124) and man. This change takes place 




Figure 124 
Genus nasalis or proboscis monkey (Library of Natural History, Vol. 1, Sec. 1). This illus- 
tration shows the period in phylogenic development when the nose is substituted for the 
snout. 

in the evolution of the face backwards. The face shortening in man's up- 
right position and from disuse of the nose and face, on account of their 
higher functions (the senses), causes these structures to degenerate for the 
benefit of the organism as a whole. 

The nose in its phylogeny becomes more complicated, since it must 
be adjusted to the general sense of smell in man's upright position. The 
dog can smell footprints and determine sex, but it only specializes and does 
not generalize as does man. 

These changes take place from the anthropoid ape type. The human 
nose is prefigured in the genus nasalis. There is, in this change, an in- 
creased use of bone for protection of sense organs, like that which occurs 
in the skull. At times, the bone increase in the nose occurs at the expense 
of the bone increase in the skull, resulting in idiots whose nose type is low 
or high but whose skull type is ape-like. 

Fig. 125 is another example of the struggle for existence between 
organs. Here again are demonstrated potentialities which pass through 
periods of stress when the newer type (the brain) competes with organs 
already existing (the face and jaws); the nasal excess of material takes 

185 



186 



DEVELOPMENTAL PATHOLOGY 



the path of least resistance and is an arrest in phylogeny at the snout 
period. The face, nose and jaws have gained at the expense of the brain. 
This child was born of healthy half-caste African parents. There is little, 
if any, brain development, while, on the other hand, the face, nose and jaws 
are well developed. There is an arrest in ontogeny of the superior maxil- 




FlGURE 125 

Phylogenic arrest at the snout period of the face, 
nose and jaws (Gould and Pyle). The face 
and jaws have developed at the expense of the 
brain and skull. 



Figure 126 
Phylogenic arrest at the snout period 
(Gould and Pyle.) The head and 
face and jaws compare favorably with 
the following figure. 



lary bone, causing cleft palate and harelip. The eyes are without lids, 
lashes or brows. The second and third fingers of both hands are webbed 
for the whole length. The right foot lacks the distal phalanx of the great 
toe, and the left foot is clubbed and drawn inward. This is typically 
atavistic of the sauropsidian character so far as concerns brain and hand 
development, and of the anthropoid ape character so far as the feet are 
concerned. The nose is of the primitive snout-like type. 

Fig. 126 also represents an individual with excessive development of 
the face, nose and jaws at the expense of the brain. Here again the snout- 
like nose is associated with a large lip resembling the lower vertebrates. 






A STUDY IN DEGENERATIVE EVOLUTION 



187 



These two illustrations show an arrest in phylogeny of the face and nose 
below the genus nasalis type (Fig. 127). 





Figure 127 

Head of an anthropoid ape 

(original) . 



Figure 128 
An Aztec idiot (Gould andPyle). Here the 
brain and the skull have become arrested 
in development for the benefit of the face, 
nose and jaws. 



Fig. 128 is that of the "Aztec man," exhibited for many years in side 
shows. This illustrates the increase in the face, nose and jaws at the ex- 
pense of bone increase in the skull, resulting in the excessive development 
of the nose above the genus nasalis — a marked arrest in phylogeny at 
the ape stage. 




Figure 129 
Excessive nose development in an idiot (Gould and Pyle) . The nose has gained at the expense 

of the brain and skull. 



188 DEVELOPMENTAL PATHOLOGY 

"Early in the last century a man named Thomas Wedders, with a 
nose seven and one half inches long, was exhibited throughout Yorkshire, 
England. This man expired as he had lived, in a condition of mind best 
described as the most abject idiocy. The accompanying illustration 
(Fig. 129) is taken from an old print and is supposed to be a true likeness 
of this unfortunate individual." Unlike the last illustration, the increase 
is in the nose alone and occurs at the expense of bone increase in the skull. 
This nose is also an excessive development in the evolution of man above 
the genus nasalis. 

In the evolution of the face, the nose has assumed certain types quite 
unlike each other; for example, the Greek, the Roman and the Hebrew are 
normal so long as they retain the type. Deviations from these types, 
however, are degenerative. Race admixture, together with changes in 
environment and disease, has caused the nose to assume different shapes. 
Roman celebrities who had long, large noses are Pompilius Numa, Plutarch, 
Lycurgus and Solon; and all the kings of Italy except Tarquin the Superb. 
Arrests in phylogeny of the nose, at the genus nasalis type, are frequently 
observed. 

External Nose — Arrest in Development in its Ontogeny. 

The nose in its ontogeny frequently becomes arrested as a result of 
disease in the parent or child. This arrest may take place at any period 
from the beginning of intrauterine formation, through any of the periods 
of stress to maturity. The most marked cases are those of congenital 
syphilis. The absence of the external nose is rare. Maisonneuve observed 
one individual in whom, in place of a nasal appendix, there was a plane 
surface perforated by two small openings. 

Fig. 130 is that of a thirty-seven-year-old, well educated school teacher 
of nervous temperament. There is arrest of the nasal bones as well as 




Figure 130 
Ontogenic arrest of the nose (original). The illustration of exceedingly bright school teacher. 



A STUDY IN DEGENERATIVE EVOLUTION 189 

the nasal cavity. The face and jaws are well developed. She is a mouth- 
breather. The chest is undeveloped. 

Fig. 131 represents a man with marked arrest of the face as well as 
the nose. This arrest must have taken place very early in childhood. 




Figure 131 
Ontogenic arrest of the nose and face (original). The face is arrested for the benefit of the 

brain and the skull. 

Many noted men have had extremely short noses. The following examples 
may be mentioned: The Due de Guise, the Dauphin d'Auvergne and 
William of Orange, celebrated in the romances of chivalry. 

A general view of the nose often reveals a want of harmony in its 
general outline. The nasal bones are arrested in development and the 
tip is turned up, from a normal or excessively developed cartilage. An- 
other very marked deformity is that in which nasal bone and cartilage are 
excessively developed. The bone takes one direction and the cartilage 
another, producing a double nose. This condition is very common among 
Hebrews. Other nationalities may also have nasal organs with material 
enough for two fair-sized noses, demonstrating a tendency toward least 
resistance in development. In a majority of such cases, total collapse of 
the walls of the nose and, frequently, mouthbreathing results. 

In over 2,000 measurements of the nasal bones, the shortest was 
found to be .40, the longest 1.6-5 of an inch in length. Even the bones 
without the cartilage would make a fair-sized nose. These bones take 
different angles. Those which are the largest take the greatest angle. 
A species of deformity, more common than generally supposed, is that in 



190 DEVELOPMENTAL PATHOLOGY 

which the nose is deflected to the right or left. This deformity, however, 
is often so great that it produces a marked asymmetry of the face, and 
just as often it is so slight as to be unnoticed by the average observer. It 
is carried to the right or left by unbalance of development in the cartilagi- 
nous structures at a period when only the soft tissues are involved. When 
the nose bones are deformed, quite another condition results. 

Marked deflection in as well as other deformities of the nose, are not 
observed in early life. As the face develops the deformity becomes more 
prominent and at puberty is well defined, although it does not reach its 
full extent until twenty -five or thirty years. In most instances, the two 
lateral halves of the face are asymmetric, as well as the nasal bones. The 
bones of the nose develop upon one side and deflect the lower border to 
the opposite side, where the bones are undeveloped. This has a tendency 
to deflect the cartilaginous septum in the same direction, which, in turn, 
exaggerates the deformity. Noses in neurotics and degenerates may be 
deflected nearly forty-five degrees from a normal position. These marked 
deflections have been charged to intrauterine injury or at birth. As the 
bones of the nose are undeveloped at birth and as marked deflection is not 
observed until later in life, such a theory fails to fit the case. An excess 
or arrest of development of the bones of the face is more likely the cause 
of such stigmata. 

The Internal Nose — Arrests in Phytogeny of the Nasal Cavity 

In the chapter upon the face, it was shown there were five types. 
The first three of these (in which the nose and upper jaw are involved) are 
of interest here. The first type comprises those faces in which the nose 
and upper jaw are well developed and are outside the perpendicular line; 
second, those in which there is an an tero- posterior arrest and are inside 
the perpendicular line; third, those in which there is a lateral arrest of the 
nose and face. The nose and upper jaw may be outside the perpendicular 
line, on or inside the line. The shape and position of the lower jaw does 
not concern us in regard to degeneration of the nose, except that arrests 
and excessive development of this bone assist in the diagnosis of the depth 
of the degeneration affecting the structures. 

Of the bones of the head, those in the face, nose and jaw region are 
the most affected by degeneracy. The severity of the arrest depends upon 
the depth of the degeneracy. These bones are m'ost affected, first, because 
of their position just below the cranium; second, because of their shape, 
position and size, all being thin with cavities between; third, because they 
are cartilaginous, derived from the chondrocranium, and are slow in cal- 
cifying; fourth, because they are fixed bones; fifth, because the arrest of 
the bones of the face takes place at the early periods of stress. 



A STUDY IN DEGENERATIVE EVOLUTION 191 

The cranium above, on the other hand, being derived from dermal 
bones is a newer acquirement of the body. It covers the brain which is 
evolving higher in development and is more persistent. The lower jaw 
develops partly from Meckel's cartilage and partly from the chondro- 
cranium, and being a movable structure, is easily influenced by an unstable 
nervous system. It may become excessively developed or arrested, but is 
more likely to develop normally than the upper jaw because of its inde- 
pendence and mobility. 

The first type of face (Fig. 94) in which the nose and upper jaw are 
well developed and extend beyond the perpendicular line are seen in those 
patients in which there is plenty of room (Fig. 132) in the nasal cavities 




Figure 132 

Arrest in phylogeny of the internal nose (original) . The septum is deflected to the left owing 

to an excessively developed right inferior turbinal bone. 

for the passage of the full amount of air. If hypertrophy, spurs and de- 
formities occur, they are of such a nature that they do not interfere to any 
extent with nasal breathing. There are seldom adenoids. The upper 
jaw is well developed. Teeth are all in normal position. The vault is 
normal in development. These patients are not mouthbreathers. 

Arrests in Ontogeny of the Nasal Cavity 

The second class of patients (Fig. 96) possess an antero-posterior 
arrest of the nose and upper jaw, in which the face is sunken. In these 
patients, there is always stenosis of the nasal cavity (Fig. 133) and the 
upper jaw is so small there is not room for sixteen teeth. The teeth are 
more or less crowded and out of shape. A V or saddle-shaped arch or 
their modifications are usually seen. 

The third class (Fig. 98) in which there is a lateral arrest of the nose, 
face and jaws have the same pathologic conditions as found in the nose 



192 



DEVELOPMENTAL PATHOLOGY 



and jaws of the second classification. In this class of cases, however, the 
external nose is long and thin. The nostrils are almost closed. 

The marked distinction between the first class of patients and the 
second and third classes is, that in the first class the bones of the face and 




Figure 133 
Nasal stenosis (original). The septum is deflected to the right owing to an hypertophied 

middle turbinate, 

upper jaw are well developed, giving plenty of room (even with a fair 
amount of hypertrophy and deformity) in the nasal cavity for the inhala- 
tion of sufficient air to aerate the blood. On the other hand, owing to an 
unstable nervous system in the parents, or disease in the child, arrests of 
development of the bones of the face in the second and third classes have 
occurred, causing an arrest of the nasal cavity, preventing the normal 
amount of air from entering the nose. In some patients, the hypertrophies, 
deformities and adenoids completely close the cavities. It is in the last 
two classifications that mouthbreathing occurs. 

An examination of the skulls of Peruvians, stone-grave Indians, 
mound-builders, cliff-dwellers, Hawaiians, etc., demonstrated that the 
width of the external nasal cavity varied considerably. In two thousand 
measurements, the greatest width was 1.25 inches. The smallest width 
was .75 inches. The length from the nasal spine to the edge of the nasal 
bones was, greatest length, 1 . 54 and the smallest 1 . 20. In neurotics and 
degenerates, when arrest of development of the face and nose has taken 
place, the width measured . 50 to . 60 of an inch and the length . 80 to . 90. 



Arrest and Excessive Development of the Turbinals 



The bones of the nose are both cartilaginous and dermal in their 
development. According to Minot, "The median ethmoidal plate sends 
outgrowing laminae of cartilage, one on each side, over the top and down 



A STUDY IN DEGENERATIVE EVOLUTION 



193 



on the inside of each nasal cavity, and from the lateral cartilage there 
appears ingrowths into each turbinal prominence. 

'There are certain parts of the chondrocranium which do not ossify, 
but are lost in the adult. The exact process by which they are resorbed 
is not known. The following parts are said to disappear: the cornua 
trabeculae; (2) the cartilage under the nasals; (3) the so-called frontal 
plate, or that portion of the orbito-sphenoid outside of which the frontal 
bone is developed; (6) the cartilaginous capsules of the sphenoidal maxillary 
and frontal sinuses; (7) parts of the turbinal cartilages. Duray has main- 
tained that some of these cartilages do not really disappear by atrophy 
but by becoming ossified and united with the dermal bones overlying 
them. Other authors doubt this theory." 

In either case, these bones are very susceptible to the influences of 
the nervous system, since they may require a long period for their calcifica- 
tion. 

Influences of disease upon the nervous system act upon these bones, 
because of their dermal nature, and cause the turbinals to become arrested 
in development (Figs. 134 and 135) before ossification takes place. The 




Figure 134 
Arrest of development of the turbinates (Zucker- 
kandl). The inspiration and expiration of air 
has separated the nasal septum on either side be- 
tween the turbinates. The cavity is rilled with 
bone tissue. 



Figure 135 
Excessive development of the turbinates 
(Zuckerkandl) . The septum is sepa- 
rated its entire length. 



inhalation and exhalation of air with an unstable nervous system stimu- 
lates an excessive development of one, two or all these bones (Fig. 136), 
according to their environment and gradual ossification. Likewise, these 
bones may never develop but are compensated for by other methods 
(Fig. 134) namely, by an increase in mucous membrane surface due to a 
thickened septum. The sides of the nasal cavity remain perfectly smooth. 
To demonstrate, these bones may become entirely arrested or excessively 



194 



DEVELOPMENTAL PATHOLOGY 



developed among the primitive races; an examination of the skulls of 
Alaska Indians and Peruvian skulls in the Army Medical Museum at 
Washington shows they possess such deformities. I have studied the 
Alaska Indians in their native country and am free to state that disease, 
especially lues, has left its mark upon them. The present descendants of 




Figure 136 
Undeveloped turbinates (Zuckerkandl) . The superior turbinates have grown and have 
taken a position midway between the inferior and middle turbinates. Owing to inspira- 
tion, the septum on the right side has become detached and has developed into the 
space between the turbinates. 

these people are as badly affected by disease and degeneration as those of 
modern civilization. 

In the development of these bones, the law of compensation is applied 
equally with all other parts of the bony framework. A given surface in 
the nasal cavity is required for the purpose of warming the air before it 
passes into the lungs. As a rule, when there is an arrest of one turbinate, 
the one on the other side is excessively developed. This is markedly the 
case in neurotics and degenerates. 



Deflection of the Nasal Septum 



I purposely reserved the discussion of the nasal septum until the last, 
for the reason that its position in the nasal cavity depends, to a great 
extent, upon the position of the turbinated bones. The septum develops 
from the primordial chondrocranium cartilage and ossifies much more 
slowly than the surrounding bones. It frequently does not become ossified, 
especially in neurotics and degenerates, until the twenty-fifth year. It 
develops in two halves; sometimes they unite, but most always in those 
children whose nervous systems are unstable they remain separated. 



A STUDY IN DEGENERATIVE EVOLUTION 195 

Along the lines of attachment, where it becomes firmly fixed and is much 
thicker, it grows faster than at the middle where it is very thin. 

Abnormal development of the bones of the nose and also their rela- 
tion to each other, begin at the first intrauterine period of stress. Because 
of the unstable nervous system, the location of these bones in their relation 
to each other differs materially. At birth, therefore, deformities and 
malposition are very common, not from traumatism, but from improper 
development. 

After birth, the inhalation of air stimulates the developing bones in 
their growth. If the growth be greater upon one side than on the other, 
arrest will take place on one side and hypertrophy on the other. The law 
of mechanics in the inhalation of air would call for the septum to take a 
position midway between the two bodies (Fig. 137). The force of air 




Figure 137 
Diagrammatic scheme of the deflection of the nasal septum (Casselberry) . The septum is 
dependent upon the position of the turbinates for its situation, the object being to 
assume a position midway and equi-distant from the turbinates. 

causes the septum to change its position, like the loose sail of a boat. All 
the bones of the nose have shortened considerably and have grown smaller 
in their phylogeny. Their tendency, then, on account of an unstable 
nervous system and also in response to the stimulus of inhalation and 
exhalation, is to grow larger in the direction of least resistance and to 
assume atavistic positions. 

The tendency of the sepjtum, influenced by inhalation and exhalation, 
is to assume a position just midway between the turbinates. It does not 
always take this position, on account of local conditions. In assuming a 
position just midway between the turbinals, because of the want of uni- 
formity, the septum takes different shapes and positions, namely, the 
shape of the letter S, again the letter C and often like the small italic 
letter /. Sometimes it is carried over so far as to approximate the right 



196 



DEVELOPMENTAL PATHOLOGY 



or left wall of the nose. When the degeneracy is marked, the position of 
the attachment, either above or below, may be located at the first period 
of stress to one side or the other. From the fact that it is attached through- 
out at its upper and lower border to a solid, bony framework, its middle 
portion is liable to bend in any direction. Deflection of the vomer, due 
to fracture of the cartilage, or the deflection of the anterior part of the nose, 
is easily differentiated from a fractured vomer. Deflection of the septum 
may take place only in the anterior, middle or posterior third of the bone. 
Sharp bends, fracture and separation (Figs. 135 and 138) of the lateral 
halves of the septum are very common. These are more marked in neuro- 




FlGURE 138 

Break in the septum between the turbinates of the right side and opposite hypertrophied 
middle turbinate of the left (Zuckerkandl) . 



tics and degenerates. The nasal cavity is small, the turbinals are arrested 
or excessively developed. There is hypertrophy of the mucous membrane 
with more or less inflammatory action. 

When inhalation takes place, the air, passing through the undeveloped 
passage, produces suction, thus drawing the bone toward that side; while 
the large volume of air passing through the other larger nostril, forces the 
bone in the same direction. Thus, by aspiration and pressure, the thinner 
part of the bone is bent to the weaker side, which gives an unequal space 
for the passage of air throughout the nose. 

When a slight irritation of the mucous membrane takes place, it 
thickens and the child experiences difficulty in breathing. In the spasmo- 
dic effort to draw air into the lungs through the nose, a vacuum is formed 
and the septum is developed and drawn to the point of least resistance, 
which would naturally be at a point between the turbinated bones. Again, 
the outer walls of the anterior nares may collapse, producing the same 
anomaly. In this manner, the septum takes the outline midway between 
the bones. The fracture very rarely extends through the two halves of 



A STUDY IN DEGENERATIVE EVOLUTION 



197 



bone (Figs. 135 and 138) only one side breaking, while the other is simply 
bent. The fractured half being always upon the convex side leads to the 
opinion that it is due (1) to the thickening of the mucous membrane, (2) 
accumulation of moisture or purulent mucus, and (3) an excessive effort 
on the part of the patient to draw air through the nose. This being im- 
possible, the vomer is drawn into the space (Fig. 138) after partial ossifica- 
tion has taken place and, as a result, fracture of that half and simple 
bending of the other half takes place. The edges of the broken half are 
torn apart from the other half, producing a space between which is eventual- 
ly filled up with bone cells (Figs. 134 and 136). This condition is not unlike 
a green-stick fracture. Sometimes it will be drawn to the right side in 
one place and to the left in another. 

Again, in the same manner, the two lateral halves are separated their 
entire length (Fig. 139). There is a projection of the right half at a point 




Figure 139 
Stenosis of the nasal cavity (original) . The septum is divided its entire length. 

of the right inferior turbinate. 



Hypertrophy 



midway between the right turbinated bones. This seems to be only 
natural, since, in many cases, the deflection and fracture only extend a 
short distance in the anterior, middle or posterior part of the vomer, while 
the bone will be perfectly straight anterior and posterior to the deformity. 
The shape of the deflection and fracture can be accounted for in no other 
way. In order that fracture may take place, the vomer must have ossified 
partially or completely, which occurs at middle life; therefore, intrauterine 
injuries or those occurring before ossification, are out of the question. If 
the turbinated bones be uniformly developed the vomer will, in most cases, 
remain quite or nearly straight. The force produced by drawing air will 
frequently separate the two halves and, occasionally, produce one fracture 
upon one side, the other upon the other side. Not only are the cartilages 
of the nose brought into close relation to each other, but, occasionally, 
the force is so great that there is a total collapse of the outer bony walls 



198 DEVELOPMENTAL PATHOLOGY 

and they are drawn toward the septum, making a groove upon either side, 
the nasal bones remaining perfectly flat at the upper edge. 

Deviation of the nasal septum to one side or the other we conclude 
is the result of an unequal development of adjacent bony parts, more 
especially and directly of that of the turbinated bones. It depends largely, 
if not exclusively, upon the development and position of these latter. 
They, in turn, are dependent in a great measure upon the development of 
the facial bones, which are modified as the facial angle increases and 
prognathism is lost — the turbinated bones being, as it were, exostosed, 
or entirely wanting, not molded in many directions by adjacent parts, 
encroaching more irregularly upon the nasal cavity, as their origins are 
disturbed or dislocated. Freedom of these nasal passages for transit of 
respired air is essential. In normal respiration the tendency is for both 
nostrils to share equally. The natural consequence is, that the vomer, 
the ossification of which is incomplete until puberty, is deflected and 
occupies, as a rule, nearly a midway position between the bony prominences 
on either side. Deflection of the septum, hence, is a compensatory arrange- 
ment for the evolutionary variations of facial development. It is therefore, 
most frequent in the higher races, while in the lower its occurrence is 
markedly less. 

Instability of tissue-building is to be expected in neurotics and degen- 
erates. It is easy to see how, with such an unstable bone tissue to build 
upon, the mucous membrane of the nose and naso-pharynx can take on 
atrophy, hypertrophy and adenoid growths, resulting in mouthbreathing. 

Total collapse of the outer walls of the nose is frequently observed 
among neurotics and degenerates. This is associated with arrest of 
development of the bones of the face, jaws, deformities of the dental arch, 
weak, contracted chest, round shoulders, husky voice. In most cases of 
this description, the nose is very long and thin. When the patient attempts 
to inhale air, the outer walls are brought together and nosebreathing is 
impossible. The result is mouthbreathing, not only taking cold air into 
the lungs, but disease germs as well. 

I have examined over 11,000 skulls in this country and Europe, 
including the large collection in the Museum of the Royal College of 
Surgeons, and 347 living individuals, with the following results: Owing 
to the fragility of the septum, the whole or anterior part was lost in many of 
the skulls, the results of which were that only 7,600 had sufficient bone 
remaining to give any idea of its shape. My examination of skulls in the 
Royal College of Surgeons, London, practically tallies with the Mackenzie 
report. In the 7,600 skulls, 5,762 showed marked deformities. Out of 
687 ancient Peruvian skulls, 147 possessed deflection of the septum. In 
69 stone-grave Indians, 35 were normal and 34 deformed. In 18 mound- 



A STUDY IN DEGENERATIVE EVOLUTION 199 

builders, 8 were normal, 10 deformed; in 6 California Indians, 4 were 
normal. 

In a collection by J. M. Whitney, of Honolulu, of 28 skulls of ancient 
Hawaiians, taken from lava caves, the jaws were unusually well developed 
as well as the bones of the face. The external bones of the nose were also 
well formed. While there was a lack of that marked asymmetry due to 
excessive arrest of development of the turbinated bones, as noticed in 
Peruvian skulls, yet the bones were far from being uniformly located in 
the cavities of the nose. There were, however, two in which the inferior 
turbinated bones were undeveloped, only rudimentary ridges being present. 
Deflection of the septum was noticed in 23 cases — some in the anterior 
part of the bone, others in the middle, and still others in the posterior part. 
In the two cases where the inferior turbinated bone was undeveloped, 
the septum deflected to that side. There were projections which seemed 
to take the place of the missing turbinates. One case was observed in 
which the deflection commenced midway, from before backwards, the 
greatest deformity being three-fourths of its distance into the left cavity, 
midway between the turbinated bones. Upon that side of the vomer, 
there was a large ridge, its greatest projection being about . 25 of an inch 
in length. Upon the opposite side there was another smaller ridge, evident- 
ly for the purpose of supporting the deflected point, and also for the pur- 
pose of affording greater surface for mucous membrane and blood supply. 
Of the 347 living persons, 107 showed deflection of the septum. 

Excessive development of the turbinated bones in ancient skulls is 
very common. Thus, in the Army Medical Museum, Washington, No. 
2,131, case 175, Vancouver Island Indians. The right middle turbinated 
bone is excessively developed, so that it fills the anterior middle space of 
the nasal cavity, with a large cavity in the center. The left middle and 
right and left inferior bones were well developed, filling both nasal cavities. 
In this case the vomer, which stands uniformly between the turbinated 
bones, takes the shape of the letter S. No. 2, 129, Vancouver Island Indians, 
shows left superior turbinated bones excessively developed to a level with 
the middle turbinated bone. The vomer is deflected to the right, then 
to the left, in order that it may stand in a central position. Skull 1,30.9, 
case 173, illustrates the theory of the author very nicely. The right 
middle turbinated bone undeveloped, inferior right excessively developed; 
the vomer at its middle takes a V-shape, in order that it may stand in the 
middle between the terminated bones. 

Spurs and supernumerary projections into the nasal cavity are, no 
doubt, due to irritations and inflammations and in many cases, are for 
the purpose of giving a larger distribution of the mucous membrane and 
to supply deficiencies. 



200 DEVELOPMENTAL PATHOLOGY 

Summary 
The External Nose 

The outer nose, in development, passes from the lower vertebrate 
snout to the beak-like type of the proboscis monkeys. On account of 
man's upright position, disuse of facial structures and the senses, the nose 
is degenerating. 

The changes taking place in nose type call for greater bone use to 
protect the organs of smell analogous to the same conditions which take 
place in skull development. 

In facial development, the nose has assumed types wholly unlike 
each other. They are normal only when there is no deviation from the 
type. 

The nose may become arrested in its ontogeny at any period from 
the beginning of intrauterine life on. The more marked deformities are 
the result of the contagions and infections. 

The nose does not always develop harmoniously; the nasal bones and 
cartilage are often arrested or excessively developed. Sometimes they 
take opposite directions producing the condition so noticeable among 
Hebrews and many other races. Mouthbreathing is often a result of 
excessive development of the nasal bones which fill the air passages. 

The abnormal development of the nasal bones and cartilages will 
cause the nose to be turned to the right or left, depending upon in which 
side of the nose marked deformity exists. The deflection of the nose 
produces asymmetry of the face, sometimes slight and again quite marked. 
Injuries in utero or at birth have been given as causes for marked deflections 
of the nose, but if one will consider that the bones of the nose are in a 
plastic state and that deflections do not occur until late in life, this theory 
is not tenable. The maldevelopment of the facial bones is probably a 
more rational theory. 

The Internal Nose 

The first three types of face only concern us in regard to nose develop- 
ment: the first type in which the upper jaw and nose are outside the per- 
pendicular line; the second, inside the line and third, lateral arrest. 

The bones of the face, nose and jaw are more often affected by degen- 
eracy due, first, to their position; second, to their shape, position and size; 
third, to their cartilaginous origin; fourth to their fixity, and fifth, to the 
early arrest of development of the facial bones. 

In the first type, where the nose and upper jaw are well developed 



A STUDY IN DEGENERATIVE EVOLUTION 201 

and outside the perpendicular line, the full amount of air can pass through 
to the lungs. Should there be deformities of any nature, there is no 
interference in nose breathing. 

In the second type, the face is sunken, due to antero-posterior arrest 
and there is always contraction of the air passages. The upper jaw is 
small with irregularities of the teeth. 

In the third type, or lateral arrest of the face, nose and jaws, the same 
conditions obtain as in the second. In this type, the air passages are 
usually closed and mouthbreathing results. 

In a comparison of the three types, a great difference will be found 
between the first, and the second and third. In the first, the bones of the 
face and jaw are well developed with ample room in the nose for normal 
inhalation and exhalation of air, with no irregularities of the teeth, while 
in the second and third types, on account of an unstable nervous system 
in one or both parents and the child, the bones of the face and jaws become 
arrested and, as a result, nasal breathing is impossible and irregularities 
of the teeth are common. Even in the skulls of the primitive races, there 
is great variation in the measurements of the nose cavities. 

Maldevelopment of the Turbinals 

The nose bones are of both cartilaginous and dermal growth. The 
turbinals are cartilage outgrowths from the ethmoidal plate and are easily 
influenced by disease, especially lues, due to their slow calcification, environ- 
ment, etc. They may be arrested or excessively developed in the primitive 
races as well as in civilized. This is nicely shown in an examination of 
Alaska Indian and Peruvian skulls and in their living descendants. Some- 
times the turbinates upon one side will be arrested while those upon the 
other will be excessively developed. 

The Nasal Septum 

The nasal septum develops in two halves from the chondrocranium 
cartilage, ossifies slowly, sometimes not at all, and its position depends 
upon the turbinals. It is more dense at its attachment than in the middle. 

Deformities and malposition of the nose bones are quite noticeable at 
birth but these are not due to injury in utero, as is generally supposed, 
but to an unstable nervous system and abnormal development. 

On account of its cartilaginous structure, the septum is easily influenced 
by inhalation and exhalation of air, which causes it to change its position, 
first being drawn to one side, then the other. 

The normal position of the septum is midway between the turbinals. 



202 DEVELOPMENTAL PATHOLOGY 

The abnormal development of these bones, however, cause it to assume 
different shapes and positions. These shapes, positions and, in some 
instances, fracture are most marked in neurotic and degenerate states and 
are more or less intense according to the depth of degeneracy. 



Chapter XVI 
THE MAXILLARY SINUSES 



IT has been shown that arrests of the face, nose and jaws in their onto- 
geny occur at the early periods of stress. Arrests, malpositions and 

irregularities of the maxillary sinuses must necessarily occur. The 
two halves of the face as well as the cavities may be asymmetrical. 

Types of Antrum are exceedingly variable. Thus in one case the 
cavity may be small and resemble a crescent with the concavity toward 
the nasal wall, the convexity toward the malar process. The cavity may 
not be large enough to admit the end of the little finger and may not 
extend as far, laterally, as the inferior orbital opening, while the opposite 
side may be similar in shape and extend just beyond this opening. Some- 
times the antrum upon one side will be very long while that upon the other 
is very small. Usually, in this condition, the nasal cavity will be carried 
over nearly one half its size to the side of the smallest antrum. There is 
sometimes soft, cancellated bone extending from the alveolar process into 
and filling the antrum, leaving a number of small openings or sinuses which 
resemble the ethmoidal cells. In these cases, the contour of the face is 
also very much disfigured. A drill passed through the alveoli of the first 
and second bicuspids would not reach the opening. 

Variations in Shape. Although the antrum is usually regarded as 
a triangle, it assumes even in normal subjects a great variation from this 
shape. These cavities, located as they are in the superior maxillary bone, 
which is always subject to arrests in development, are difficult to outline, 




Figure 140 

Maxillary sinuses extending close to the median line (Zuckerkandl) . The opening for these 

cavities into the nose is located at the upper border. The antra are filled with septi. 

203 



204 



DEVELOPMENTAL PATHOLOGY 



Septa are most always present, which partition the cavity into smaller 
compartments. In the large number of antra examined, I have always 
found that these septa are attached to the lower border of the cavity 
extending upon either side. In most cases, there is an opening at the 
upper border of the septum which prevents the division of the larger 
cavity into separate and complete smaller ones. It is well to bear this in 
mind when draining the cavity, since the cavity opened may become well 
drained while others may remain full of fluid. The variations which may 
occur are best illustrated in the contrasts between the following cases. 

One extreme in variation is Fig. 140 in which the antra, while not 
alike in size, are peculiarly situated as to location. The external and 
internal walls are quite thin, allowing for unusual size. They extend 
almost to the median line and encroach upon the nasal cavity. There are 
ridges of bone and septa extending throughout the cavity, which are not 
uncommon in those jaws where the depth of degeneracy is marked. Fig. 
141 is an extreme in variation in the opposite direction. The na^al cavities 




Figure 141 
Arrest of the maxillary sinuses and the nasal 
cavities extending beyond the alveolar process 
(Zuckerkandl) . 



Figure 142 
The nasal cavities developed to the left side of 
face (Zuckerkandl) . The frontal sinuses, the 
antra and the nasal cavities are made up of 
small cavities owing to the depth of the 
degeneracy. 



extend laterally and encroach upon the small antra. The middle and 
inferior turbinates have developed and adjusted themselves uniformly 
throughout the cavity. 

Degeneracies. Fig. 142 illustrates the depth of degeneracy to a 
marked degree. The maxillary sinuses and the nasal cavities are almost 
obliterated and the spaces are filled with small cavities. Arrest of the 
maxilla is more marked in the right, and the left antrum and nasal cavity 
are blended in one cavity. The septum has separated and developed to 



A STUDY IN DEGENERATIVE EVOLUTION 205 

the left. This is a splendid illustration of the struggle necessary in so 
degenerate a structure to inhale and exhale air, carrying the septum to the 
center of the nasal cavities, regardless of obstacles. The attachment at 
the floor of the nares, while in a plastic state, has been actually forced to 
the left for this purpose. Two small cavities appear beneath the left nasal 
cavity. The alveolar process and maxillary bone are continuous. The 
left antrum is entirely obliterated. 

Fig. 143 illustrates an arrest of the right and excessive development 
of the left antrum, which extends downward in the alveolar process. The 




Figure 143 
Arrest of the right antrum and excessive development of the left (Zuckerkandl) . Septa are 

seen in both antra. 

position of these cavities in their relation to the alveolar process and to 
the nasal cavity are interesting. The antra are partitioned by septa. 

Fig. 144 is of interest because the roots of the teeth covered with a 
thin bony plate and mucous membrane extend into both cavities. When 
death of a dental pulp occurs, inflammation and abscess are likely to occur 
upon the ends of the root, causing in turn inflammation of the lining 
membrane of the cavity. 

These illustrations are interesting because of their anatomic relations. 
In opening the antrum, many operators are of the opinion that the roots 
of the teeth are in direct line with the sinuses (Fig. 144) and for this reason 
open this cavity through the alveoli. A close study of the illustrations, 
show that the opening would occasionally pass directly through the floor 
and into the nose, or, as in some others, it would be almost impossible to 
find the antrum. 

Abnormalities. On examination of skulls, I have discovered some 
eight cases where the floor of the nose was so wide and the facial bones 
so deformed that the long axis of the roots were directed into the floor of 



206 



DEVELOPMENTAL PATHOLOGY 



the nose. In each case, the floor of the nose would be perforated were 
the operator to drill through the palatine and buccal cavities made vacant 
by the roots of the first or second molars. I have frequently observed 
arrest of development of the maxillary bone on a line with the alae of the 
nose, when the alveolar process (in order that the upper teeth might 
antagonize with the lower) extended outward to such an extent that the 
apices of the roots of the bicuspids would point entirely outside the line 
of the antrum. Hence the alveoli are not a reliable route by which to 
reach the lowest point in the floor of the antrum, nor is the operator sure 
of reaching it at all. It is easy to see how in a very few cases the develop- 
ment of the antrum and nasal cavities might be such, together with the 
thinness of the alveolar process, that the roots of the teeth may penetrate 




Figure 144 
The roots of the teeth extend into the antrum (Zuckerkandl). 

the floor of the antrum. These cases, however, are rare. In most cases, 
owing to the thickness of the alveolar walls and the position of the antrum, 
the roots of the teeth will not reach it. The roots of the first and second 
bicuspids almost never enter the floor of the antrum. The roots of the 
first permanent molar in its relation to the antrum are such that it is 
almost impossible to penetrate it. 

Diseased Conditions. Dr. M. H. Fletcher, of Cincinnati, in an 
examination of 500 skulls (making 1,000 antra) found 252 upper molars 
abscessed, making twenty-five per cent of antra which have abscesses in 
this locality, or every fourth antrum. This per cent is probably smaller 
than it should be, since many teeth were lost and the alveolar process 
absorbed. Undoubtedly some of these lost teeth had been abscessed. 
Out of these 252 possible cases, perforation into the antrum was found 



A STUDY IN DEGENERATIVE EVOLUTION 207 

only twelve times; thus showing over four and one-half per cent, or about 
one in every twenty-one of the abscessed teeth in this locality, which are 
connected with the antrum. 

In my own examination of 11,000 skulls, only 3,000 were found in a 
broken condition so that the antra could be examined, making 6,000 antra 
in all. Of this number 1,274, or about 21 per cent had abscessed molar 
teeth. Of this number 76, or about 6 per cent, extended into and apparently 
discharged into the antrum. As specialists were unknown among the 
ancient people whose skulls were examined, a larger percentage of abscessed 
cavities would occur than at present, due to lack of treatment. Septa 
were found in 963 cases. These ranged all the way from a simple ridge 
running along the floor to a partition extending two-thirds the height of 
the cavity. Again, several septa occurred in all directions which gave 
the appearance of ethmoidal cells extending throughout the entire cavity. 

Dr. M. H. Fletcher found in 224 cases of pulpless molar teeth among 
his patients only one case of pus in the antrum. In the treatment of 367 
cases of pulpless teeth in connection with the superior molars in the past 
forty years, only three cases of diseased antra were noticed by me, making 
less than three per cent of diseased antra. 

In the treatment of diseases of the maxillary sinuses, dead teeth and 
their abscesses should first be considered and excluded before considering 
other causes. Owing to the variation in location and deformity, the 
safest operation is to enter the antrum through the nasal cavity, at which 
point it can be thoroughly explored, drained and treated. The patient 
should be requested to lie first upon the back; then upon the face with the 
head down. Should there be any septa in the sinus, the fluid will, in this 
way, be easily drained. 

Summary 

At the early periods of stress when arrests of the face, nose and jaws 
take place, it necessarily follows that the maxillary sinuses must be involved 
at the same period. 

Of all the sinuses, the antrum is probably the most variable. It 
assumes various shapes, may be large or small and is often filled with 
septa which separate it into several cavities. The treatment of the antrum 
when septa are present is difficult, owing to the fact that one cavity may be 
well drained while others remain in a diseased state. Located as it is in 
the superior maxillary bone, which is always influenced by an unstable 
nervous system, the antrum even in supposedly normal individuals may 
be far from a triangular shape usually considered normal. 

Extremes in the location, size, density, etc., have been nicely brought 



208 DEVELOPMENTAL PATHOLOGY 

out in the illustrations, which also show how markedly this cavity is affected 
by degeneracy. 

Many operators believe that the roots of the teeth are in direct line 
with the antrum and therefore attempt to open it through the alveolar 
processes. This is not a safe procedure as oftentimes an opening will be 
made through the floor of the nose and the antrum never be reached. 

From skull examination, I have found eight instances where the 
roots of the teeth were directly in line with the floor of the nose and an 
operator using the sockets of the first or second molars w T ould penetrate 
the floor of the nose. Frequently arrest of the maxillary bone causes the 
alveolar process of the jaw to protrude to the extent that the ends of the 
bicuspid roots will be entirely away from the antrum. So to open the 
antrum through the alveolar process is a very risky operation. There 
are rare instances, however, in which the roots of the teeth penetrate the 
antrum floor. Seldom do the roots of the bicuspid teeth enter the antrum 
and the first permanent molars never. Dr. M. H. Fletcher's examination 
of 500 skulls and my own of 11,000 bear out this conclusion. The safest 
method to enter the antrum is by way of the nasal cavity. 



Chapter XVII 
THE JAWS 

THE variability in human jaw development is easily understood 
when one takes into consideration the evolution in phylogeny, 
the factor of disuse, the dermal structures and the various obstacles 
encountered in ontogeny. 

The shortening of the jaws from before backward; the diseases encoun- 
tered in parent and child involving the nervous system; the fixed position 
of the upper jaw, it being developed in connection with the bones of the 
skull; the mobility of the lower jaw and its development independent 
of all the other bones of the body, — the wonder is that the teeth ever 
develop in harmony with each other. While it is true that in any given 
patient the two halves of the body may be asymmetric, the contrast between 
the two halves because of their distance from each other, is not nearly so 
noticeable as a like degree of asymmetry in the jaws and teeth. The 
minutest detail in contour, shape and position of the jaws is immediately 
detected because of their close proximity and because of their appearance 
in facial expression. The position of the teeth is also readily observed, 
since symmetry adds greatly to the appearance of the individual. 

In the study of deformities of the face, nose, jaws and teeth the fact 
must not be lost sight of that, when these structures are involved, the 
line of least resistance may be in both directions, therefore excessive 
development of these structures may ensue as readily as arrest. 

The tendency in jaw development is along the line of least resistance, 
that is, toward large well developed jaws like those of our ancestors (Fig. 
91). Disuse of structure and disease has obtained mastery over their 
development, and the material intended for jaw development has been' 
appropriated, under the law of economy of growth, to other structures, 
namely, the brain and skull. Owing to an unstable nervous system, it is 
possible for atavisms manifested in large jaws to occur. Hence both jaws 
may in some persons develop like those of our ancestors, or one jaw may 
develop large and the other small. The larger one is an arrest in phylogeny 
and the smaller an arrest in ontogeny. Again part of one jaw, as the body 
of the lower, may develop large and long, while the rami may be normal 
in size or arrested in development, or the rami may develop large and long, 
arrest in phylogeny, and the body be normal in size or arrested in onto- 
genetic development. Again one side of the rami, or body, or both, of the 
jaw, may become excessively (phylogenetic) developed and the other side 
remain normal or arrested in ontogenetic development. 

Under such conditions, the face not only becomes markedly deformed, 

209 



210 DEVELOPMENTAL PATHOLOGY 

but the teeth are also irregular and out of their normal position. In an 
examination of 1,977 idiots, there were found to be 159 with protruding 
superior maxilla and 92 with protrusion of the inferior maxilla. In an 
idiot boy of thirteen at the Hamburg, Prussia, School of Idiocy, the lower 
jaw was excessively developed one and one-half inches beyond the upper. 
The upper jaw is more liable to become arrested than the lower. 
This is due to the fact that marked arrests take place in utero at the first 
period of stress (Fig. 145 — a skull at birth). The brain continues to 
develop in all directions extending forward over the face. The lower jaw 
is less liable to become arrested because of its mobility and because it is 
developed independently of the other bones of the body. When, however, 
arrest of the lower jaw does occur, it is always an indication of marked 
depth of degeneracy, to which the system of the child is subjected, as in 
idiocy, rickets, tuberculosis, etc. 




Figure 145 
Skull at birth showing arrest of the face and superior maxilla (Spoldeholtz) . 

The accustomed eye can easily detect the degenerate face and jaw 
bones (arrests in ontogeny) at birth. In studying the skulls (Figs. 44 and 
45), the one at ten months shows arrest at the nasal bone, while the skull 
at birth shows a marked arrest of the face. The lower jaw at seven months 
and that at twelve months shows excessive development. The face at 
twenty-two months and at two years is markedly arrested, while the lower 
jaw at three years and six months is also arrested. All these deformities 
may become more exaggerated in bone development or they may develop 
near the normal. 

The changes which take place in the jaws and teeth are best studied 
in the negro. Those children who are the descendants of three or four 
generations living in the older cities, especially in Boston, are of interest. 



A STUDY IN DEGENERATIVE EVOLUTION 211 

Here the great changes are marked and represent not over 250 years. 
The same degeneracies in the Caucasic race have required thousands of 
years. Arrest of the jaws in very marked degenerate children from one 
to five years of age with deformed dental arches are occasionally seen. 

Arrests and excessive development of maxillary bones, however, are 
not very pronounced in connection with the first set of teeth. They do 
not develop their full degree of degeneration until the individual is from 
twenty to thirty years of age. A few of the more marked deformities, 
frequently observed by the stomatologist, are here illustrated. 

Fig. 146 represents the jaws of a patient, twenty-six years of age, in 
whom, on examination, was found a small normal inferior maxilla, well 




Figure 146 
Excessive development of the superior maxilla (original). 

protruded and in harmony with the other features of the face. The 
superior maxilla and alveolar process were excessively developed, the first 
molar and anterior teeth describing a much larger circle than the lower. 
The second molars were the only teeth that articulated properly. The 
anterior alveolar process had taken on a prolific deposition of bone cells, 
until the teeth impinged upon the gum of the lower jaw, producing absorp- 
tion. The upper jaw may be considered an atavism and arrest in phylog- 
eny, while the lower is an arrest in ontogeny. The upper lip was covered 
with a mustache which completely hid the deformity. Under such condi- 
tions a prominence is observed at the alae of the nose — the upper lip being 
drawn tight over the alveolar process. The cause of this class of cases 
may be a local one. 

Fig. 147 represents a case occasionally met with. The body of the 
inferior maxilla is excessively developed, the extent of the irregularity 
depending on the degree of development. When only a slight protrusion 
exists, the inferior incisors strike beyond the superior incisors. In extreme 
cases only the molars articulate. When the anterior teeth articulate, the 



212 DEVELOPMENTAL PATHOLOGY 

alveolar process develops so that the teeth extend to the superior alveolar 
process. The features may be otherwise quite regular. Asymmetry of 
the jaws often continues to develop until the osseous system has obtained 





Figure 147 Figure 148 

Excessive development of the lower Excessive development (hypertrophy) 
maxilla (original). of the superior alveolar process 

downwards (original). 

its full growth. The upper jaw is an arrest in ontogeny, while the lower 
jaw is an arrest in phylogeny. This deformity is common among negroes. 

Fig. 148 is that of a fourteen-year-old boy. Before the eruption of 
the second molars, the articulation was perfect. As soon as the second 
molars occluded, the jaws were forced open. This deformity is due to two 
causes ; first, there is an excessive development downward of the alveolar 
process; second, the rami are so short that when the second molars devel- 
oped the line of articulation was changed. The inferior maxilla is 
not well developed, nor has it the power to overcome the resistance and 
force the superior alveolar process and teeth forward, as exemplified in 
next illustration. 

When the rami are so short that they do not harmonize with the 
maxillary bones, the movement of the jaws may be likened to that of the 
arms of shears; the farther the points are from the center, the greater the 
distance they have to travel. A slight movement at the center will cause 
them to move a considerable distance. In a similar manner, a slight 
excessive protrusion of a molar will cause the anterior teeth to become 
separated. The shorter the rami, the less the harmony between the jaws 
and teeth; the farther back the protruding molar and the more it projects, 
the greater the anterior separation of the jaws. The excessive eruption of 
the second and third molars is very often due to the person's sleeping with 
the mouth open; the pressure upon the posterior teeth being removed,. 



A STUDY IN DEGENERATIVE EVOLUTION 213 

the alveolar process will elongate and carry the teeth downward. Not 
infrequently the malocclusion of the teeth is due to the inability to close 
the jaws on account of the inharmonious development. 

Occasionally there are mouths in which the molars and bicuspids 
occlude, and there is just enough space between the centrals to admit a 
thin spatula. In January, 1887, a patient was brought to the writer for 
advice whose jaws, when closed, showed a space of half an inch between 
the incisors. Such cases are due to arrest of development of the anterior 
alveolar process, the superior dental arch being too small for the inferior. 
The pressure of the jaws upon the molar teeth is, in some instances, so 
great that normal eruption is impossible. In such cases, the molars will 
protrude through the gum and the superior and inferior processes will 
occlude when the jaws meet. 

Fig. 149 shows the opposite condition to Fig. 148. Here the upper 




Figure 149 
A weak upper alveolar process and a strongly developed lower jaw (original) . Arrest of the 

rami is quite noticeable. 

jaw is the weaker of the two. The rami is short and there is a want of 
harmony in jaw development similar to the last illustration. The force 
of the heavy lower jaw against the weaker upper has carried the teeth and 
alveolar process forward until articulation is normal. The result is, how- 
ever, that the incisors and alveolar process protrude in front. 

Fig. 150 shows an excessive development of the rami and an arrest of 
development of the body. The excessive development of the rami has 
caused the body of the jaw and the teeth to protrude beyond the upper 
teeth. When such a deformity is associated with arrest of development 
of the superior maxilla, it is extremely difficult to restore the features to a 



214 



DEVELOPMENTAL PATHOLOGY 



normal expression. In this illustration, the second molar on the upper 
jaw and the third molar on the lower were found to be the only teeth 
that occluded. In connection with this deformity, there was a marked 
arrest of development of the bones of the face. 

Fig. 151 shows the reverse of Fig. 150. There is an arrest of develop- 
ment of the rami and excessive development of the body of the lower jaw, 





Figure 150 
Excessive development of the rami (original). 
The body of the jaw for this reason has 
been carried forward. 



Figure 151 
Reverse condition of Fig. 150 (original). 
A marked arrest of development of the 
rami with excessive development of the 
body allowing the teeth to*' articulate 
normally. 



with a protruding chin. The lower jaw is small, thin and very delicate. 
In such patients, dislocation of the inferior maxilla is liable to occur while 
yawning, scolding, or during dental operations, so great is the leverage. 

Excessive development of the jaws is not uncommon. It frequently 
takes the direction of least resistance, arrest in phylogeny, and resembles 
the lower negro type. In such patients the muscles are large and heavy, 
the jaws well set and the teeth large and evenly located without irregulari- 
ties. When the jaws are developed larger than the type (atavistic), the 
teeth are always large and hard, the surfaces smooth and they seldom 
decay. 

Fig. 152 illustrates a normal superior maxilla and rami, with arrest 
of the body of the jaw, including the chin. The deformity is a very common 
one, most markedly observed among idiots, and produces an unsightly 
appearance. 



A STUDY IN DEGENERATIVE EVOLUTION 



215 



Fig. 153 is that of a young lady twenty-three years of age, reported 
by Dr. Vilray Papin Blair, in the Journal of the American Medical Associa- 
tion for July 17, 1909, showing an arrest of the inferior maxilla. She had 
scarlet fever at two years with mastoid suppuration of each ear. 




-js^^yflfe 




' 


E» 


mm- 









Figure 152 Figure 153 

Arrest of the body of the lower jaw Arrest of the inferior maxilla (V. P. Blair), 

(original) . 

Complete absence of the inferior maxilla, as Gould remarks, is much 
rarer in man than in animals, but it does occasionally occur (Fig. 154). 




Figure 154 
Complete absence of the lower maxilla (Sutton). Opening at the first gill cleft. An arrest 
in phylogenic development at the fish stage. The ears are developed out of their normal 
position. 

Nicholas and Prenent have described a case of this in a sheep. Gurlt has 
observed cases with total or partial absence of the inferior maxilla. Simple 



216 DEVELOPMENTAL PATHOLOGY 

atrophy of the inferior maxilla occurs in man and the lower animals, but 
is much less frequent than atrophy of the superior maxilla. Langebeck 
reports the case of a young man who had the inferior maxilla so atrophied 
that in infancy it was impossible for him to take the breast. The patient 
had nearly complete immobility of the jaws. Boullard reports a facial 
deformity with deficiency of the condyles of the lower jaw. Maurice has 
reported a vice of conformation of the lower jaw which rendered lactation 
impossible. Tomes describes a lower jaw, in which the development of 
the left ramus had been arrested. Canton describes an arrest of develop- 
ment of the left perpendicular ramus of the lower jaw, combined with 
external malformation. Animal breeders have taken advantage of these 
peculiarities in jaw development and have developed types which have 
become fixed. Thus, the domestic hog has been developed with very 
short jaws, which were originally very long. Different breeds of dogs 
have been raised, some with long jaws, others with short and still others 
with the upper jaw arrested in development, all of which sprang from the 
original wolf dog. It will be seen, therefore, that since such deformities 
may easily be produced by deliberate purpose in the lower vertebrates, 
they may occasionally occur by fortuity in jaw irregularities among the 
human. In like manner the shortening of the human jaws may be pro- 
duced by the continual extraction of the temporary and permanent teeth, 
generation after generation. The vicious habit, so common in some 
countries, of extracting the first permanent molar to prevent crowding, 
will produce the same result. The rapid decay of the teeth, thus prevent- 
ing the crowding of the crowns against each other to expand the arch, is 
another fruitful cause of jaw arrest. By the careful observer many other 
deformities of the jaws, not here illustrated, will be found among the 
defective classes. 

Summary 

Evolution and disuse together with other ontogenetic conditions 
play an important part in the development of man's jaws. The shortening 
of the jaws, neurasthenic conditions in both parents and child, fixity of 
the upper and mobility of the lower influence the eruption of the teeth. 
While asymmetry of other parts of the body may escape observation, 
any variation in jaw development and tooth irregularity is easily detected. 

Disuse, disease, an unstable nervous system, too early or too late 
extraction of the temporary teeth, together with brain and skull gains in 
human evolution, have caused the jaws to become arrested or excessively 
developed. These stigmata of jaw degeneracy are well illustrated in 
idiocy. 



A STUDY IN DEGENERATIVE EVOLUTION 217 

The lower jaw, on account of its independent development and mobility 
is not so easily affected by degeneracy as the upper, which often becomes 
arrested at the first intrauterine period of stress. The evolution of the 
negro in 250 years is the best example of jaw and tooth change. There is 
rarely arrested or excessive development with the deciduous teeth. The 
deformities occur later in life in connection with permanent tooth eruption. 

Large or excessively developed jaws are an atavism and resemble the 
lower negro type. ' In these instances the muscles are tense, the teeth well 
developed and hard without decay or irregularities. 

Instances of the absence of the lower jaw have been reported by many 
investigators. 



Chapter XVIII 
THE DENTAL ARCHES 

DENTAL arches of early races, as observed in their skulls and those 
of primitive races now living, do not show the deformities seen in 
modern races. 
In the evolution of man, his jaws and teeth attained their highest 
physical development when they reached the perpendicular line (Fig. 92) 
and still contained thirty-two well developed, hard, sound teeth, in their 
proper positions, with plenty of room between the third molars and the 
angle of the jaw. Such jaws and teeth are to be found in primitive early 
races. Some of the jaws of the more primitive races measured %% to 3 
inches in lateral diameter (Fig. 155). Since that period man's jaws have 




Figure 155 
A normal dental arch (original). This arch is a little larger than the average normal at our 

present stage of evolution. 

degenerated, the normal jaw of the Caucasic races now having an average 
measurement of about two inches. 

Line of Jaw Development. A study of the jaws and teeth of 
peoples living today will demonstrate that deformities of the dental arch 
increase in proportion to the evolution and degeneration of the face inside 
the perpendicular line. In nationalities where the jaws are the smallest 
(English) the most marked deformities of the dental arch are observed. 
Arrest and excessive development of the jaws due to an unstable nervous 
system in parent and child furthers the diminution of the already small 
jaws. While the evolution of man, in which the brain is growing larger 
and the face and jaws are growing smaller, is a normal healthy process, it 

218 



A STUDY IN DEGENERATIVE EVOLUTION 219 

is the unstable nervous system which causes the further arrest. In large, 
well developed jaws, there is plenty of room for thirty-two well developed 
teeth. These teeth are situated in their normal position. As the jaws 
grow smaller, the teeth do not decrease in size to correspond to the size 
of the jaw hence irregularities occur. The reason for this want of harmony 
in tooth and jaw development is interesting. All structures of the body 
develop, as we have seen, from a primitive cell. This cell divides into 
two cells, these into four, four into eight and so on until the structure has 
developed to its full size. While this development in ontogeny is going on, 
arrests may take place at any period before full growth has occurred. 

The Development of the Teeth, however, is an exception to this 
rule. The dental papilla follows the same law, and is influenced by sys- 
temic diseases like other structures. The teeth, therefore, do change 
their shapes and do grow smaller in the evolution of man, but not in pro- 
portion to the evolution of the jaws. The enamel organ, on the other 
hand, is developed from a fullgrown epithelium and not from a primitive 
cell. This epithelium, when it has assumed the shape of the tooth to be 
formed, calcifies at the periphery of the dentin bulb, thus fixing the shape 
and the size of the tooth. The rule of ontogenetic development, therefore, 
does not obtain in the enamel organ. While such marked diseases as 
syphilis, tuberculosis, etc., in parents and the eruptive and constitutional 
diseases in children will, to a certain extent, affect the enamel organ in its 
local arrangement of epithelial cells before or at the time of calcification, 
the depth of degeneracy is not so great as it is upon tissues of the body 
developing from a single cell, especially the jaws. 

The eruption of the teeth, if they develop in their natural order and 
position, will wedge their way, to a certain extent, and enlarge the jaw. 
Not infrequently the arrest is so great, and, because of an unstable nervous 
system, the bone cells are deposited in such a dense form that the force is 
insufficient to produce absorption and enlarge the jaw. The alveolar 
process builds itself naturally about the roots of the teeth, no matter how 
large, small, or irregular the dental arch may develop. 

Irregular Dental Arches (individual) are rarely, if ever, observed 
in connection with the temporary teeth. This is due to the fact that the 
jaws continue to grow during the second and third periods of stress. The 
stimulation of bone cells in developing the jaws is, no doubt due, in a degree 
to the irritation set up by the dental crypts of the second set of teeth. 
This environmental stimulus is sufficient, in many cases, to overcome the 
general arrest of the jaws at this time. 

When, however, irregularities of the dental arch occur with the first 
set of teeth, the antero-posterior or lateral degeneracy is most severe upon 
the face and jaws, at or before the second period of stress. Occasionally 



220 



DEVELOPMENTAL PATHOLOGY 



there is some local cause, as sucking of the thumb or other substances or 
other local interference. 

An irregular dental arch of the second set of teeth is a purely local 
mechanism. Given a small arrested jaw, on the one hand, and a set of 
teeth the long diameter of which, when in normal position, describes a 
larger circle than the circle of the jaw, on the other, a break must 
essentially take place at the weaker parts of the jaw circle. 

The development of the teeth and the position they occupy upon 
both sides of the median line, are rarely alike. The reason for this is 
that the environment is rarely the same upon the two sides. The two 
sides of the jaw may not develop alike owing to an unstable nervous system; 
one side may have a more dense deposit of bone cells than the other; 
there may be hypertrophy of bone upon one side and not upon the other. 
The germs of the teeth may not be located in identical position on both 
sides. In the eruption of the teeth, obstacles may be in the way of a 




Figure 156 
A V-shaped dental arch (original). 



Figure 157 
A saddle-shaped dental arch (original). 



normal healthy development and position, during or after eruption. Since 
the two halves of the jaw do not develop alike, for a clear understanding 
of the position taken by the teeth, an imaginary line must be drawn through 
the jaws at the median line dividing the superior and inferior dental arches 
into two lateral arches upon each jaw; the first permanent molars being 
the posterior bases, the central incisors the anterior bases and the cuspids, 
the keystone to each lateral arch. This order is the basis for the develop- 
ment of the V dental arch and its modifications. In the formation of the 
saddle arch and its modifications, the anterior base is changed from the 



A STUDY IN DEGENERATIVE EVOLUTION 



221 



central incisor to the cuspids which then become the fixed point, or base, 
in the anterior dental arch. 

The Eruption of the Teeth is not unlike a game of checkers or 
chess. Upon the wisdom displayed in the first few moves will depend 
who wins the game. The same is true in regard to the type of irregular 
dental arches. 

There are two typical forms of irregularities of the teeth, namely the 
V dental arch (Fig. 156) and the saddle dental arch (Fig. 157). All other 
deformed dental arches are simply modifications of these two. Which 
form of dental arch develops in a given jaw will depend upon which teeth 
erupt first and the time of the eruption, after the first permanent molar 
is in place. Eruption of this tooth is the first move in the game. It must 




Figure 158 
A partial V-shaped dental arch (original). 



Figure 159 
A semi- V-shaped dental arch (original). 



not be assumed that irregular tooth development is a game of chance and 
that the teeth come into place in haphazard fashion; such is not the case. 
The position the teeth assume in the V and saddle arches, and the position 
they try to assume in their modifications (but are interfered with by 
environment), is governed by laws (phylogeny and ontogeny) just as fixed 
as the laws which govern malformed structures in other parts of the body. 
The jaw bones per se are an arrest in ontogeny, while the V dental arch 
is an arrest in phylogeny at the fish and reptile stage and the saddle dental 
arch at the carnivora stage. 

The Classification of Deformed Dental Arches was not an easy 
matter. It required eight years and a collection of more than 3,000 models. 
The more marked forms were first placed into groups, then the less marked, 
and so on until all had been grouped. From these groups, the following 
forms were obtained. No two models were exactly alike, showing con- 



222 DEVELOPMENTAL PATHOLOGY 

clusively that the malformations could not possibly be moulded by any 
external process. 

Fig. 158 shows a partial V-shaped dental arch, Fig. 159 a semi-V. 
Fig. 160 presents a partial saddle-shaped dental arch, Fig. 161 a semi- 
saddle. 

A closer observation will disclose a group of models in which there is 




Figure 160 Figure 161 

A partial saddle-shaped dental arch (original). A semi-saddle-shaped dental arch (original), 

a blend between the V and saddle-shaped dental arches (Fig. 162). There 
is a great variety of these two forms, influenced by local environment in 
tooth eruption. They would assume the definite V or saddle-shaped forms 
were it not for local interference. 




Figure 162 
A V and saddle-shaped dental arch combined (original). 



A STUDY IN DEGENERATIVE EVOLUTION 223 

Deformed dental arches due to local environment are not considered 
in this work. These and the details of the formation of the V and saddle- 
shaped arches and their modifications have been fully explained in the 
author's work "Irregularities of the Teeth." 

Summary 

The acme of perfection in the teeth of man is marked by the perpendic- 
ular line, by thirty-two well-developed teeth, and plenty of room between 
the third molar and the angle of the jaw. This perfection is most observ- 
able in primitive races. 

Deformities of the dental arch are in proportion to the evolution of 
the face inside the perpendicular line (degeneration). 

The teeth, while they do grow smaller in the course of evolution, do 
not keep pace with the diminishing jaw. To this are due irregularities 
of the dental arch. 

These irregularities rarely occur during the first teeth, as the jaw is 
then still growing. 

Irregular development of the dental arch is asymmetrical, because 
the environmental influences are not the same upon both sides. 

The types of arch are determined by the disposition of the first few 
teeth erupted, and are defined according to an imaginary median line. 

There are two general types, the V and the saddle arch, of which all 
others are modifications. 

These two types are arrest in phylogeny, the V dental arch to the 
fish and reptile, the saddle dental arch to the carnivora. 



Chapter XIX 
THE ALVEOLAR PROCESS 

THE alveolar process (Fig. 163) is a soft, spongy, provisional bone, 
situated upon the superior border of the inferior maxilla and the 
inferior border of the superior maxilla. These bones are considered 
a part of the maxillary bone and are so described by anatomists. They 
should, however, be considered as practically separate and distinct bones, 
for the reason that they are exceedingly transitory. Their structure and 




Figure 163 
The upper jaw and alveolar process after the teeth have been removed (original). 

function, moreover, differ completely from the structure and function of 
the maxillary bones. 

Development of Alveolar Process. At birth, the alveolar process 
is not present. It does not make its appearance until the first teeth develop. 
At birth, the sacs containing the crowns of the teeth are nearly or quite 
enclosed in their soft bony crypts. When the teeth erupt, the alveolar 
process, being soft and spongy, moulds itself about the roots after their 
eruption, regardless of their position in the jaw. As the teeth erupt, the 
alveolar process develops upward and downward with the teeth until it 
attains the depth of the roots of the teeth, which extend, in most instances 
into the maxillary bone when the roots of the teeth have completely 
developed. The teeth develop upwards and downwards until a resting 
point is acquired which is in harmony with the development of the rami. 
The depth to which the roots penetrate the bone differs in different mouths. 

This depends upon the length of the root and the alveolar process. 
The fact that some of the teeth are fixed in the bone itself as well as in the 
alveolar process makes the correction of some forms of irregularity more 
difficult, for not only is the process re-shaped, but the bone as well. This 
is quite noticeable in correcting irregularities of the teeth in the lower 
maxilla. The crypts of the permanent teeth are located at the apices of 
the roots of the temporary teeth. The permanent teeth have large crowns 

224 



A STUDY IN DEGENERATIVE EVOLUTION 225 

and long roots, which require a much larger circle in the jaw and alveolar 
process. It is natural, therefore, as man develops and grows in size, for 
the jaws and alveolar process to develop larger for the second teeth to 
come into their normal position. 

In the previous chapter, it has been shown the two lateral dental 
arches do not develop uniformly; one lateral dental arch may be normal, 
while the other may be a V, saddle-shaped, or some one of their modifica- 
tions. Again, one. lateral dental arch may be a V or saddle-shaped and 
the other a mixture of both (Fig. 162). The alveolar process will mould 
itself about the roots of these teeth and change the shape of the vault to 
correspond with the contour of the teeth. 

The alveolar process is composed of two plates of bone, an outer and 
inner, which are united at intervals by septa of cancellous tissue. This 
form of alveoli is for the reception of the roots of the teeth. In some cases, 
the spreading of the maxillary bones by wedging, as the teeth come into 
their normal position, is so great that the deposition of bone cells cannot 
develop in harmony with the size of the dental arch. Not infrequently, 
the buccal surfaces of the roots of healthy teeth extend nearly or quite 
through the outer bony plate and are only covered by the peridental and 
mucous membranes. The inner plate is thicker and stronger than the 
outer, for the reason that absorption of the alveolar process does not keep 
pace with the lateral advancement of the rapidly growing maxillary bone, 
because of lateral pressure. Discrepancy in development of the outer 
and inner plates of the alveolar process is thus accounted for. The thin- 
ness of the outer plate of the alveolar process, and its frequently observed 
absorption, due to irritation by too vigorous use of the tooth brush over 
the cuspid and other teeth, results. 

In jaw evolution with arrest of development, there develops, in some 
instances, a high vault. There is a tendency also to lengthening of the 
rami, owing to an unstable nervous system. The crowns of the teeth also 
are changing their shape owing to the evolution of the face. The teeth 
are growing smaller in diameter, but longer in length of roots. This is a 
good illustration of the law of compensation, for since the jaws are growing 
smaller the roots are obliged to lengthen to support mastication. 

With these natural changes, and because in many cases the nasal 
cavities are smaller and filled with hypertrophied bone and mucous mem- 
brane, mouthbreathing results. Any one or all these conditions cause the 
jaws to assume a wider distance between each other. It is natural for 
the alveolar process to grow upwards and downwards until the teeth come 
in contact with a resistance. The lengthening of the alveolar process, there- 
fore, produces a higher vault, no matter what the size of the dental arch may be. 

Function and Mechanism of Alveoli. The alveoli are lined with 



226 DEVELOPMENTAL PATHOLOGY 

a thin plate of bony substance extending from the outer and inner plate 
of the alveolar process to the apex, where there are small openings for the 
entrance of nerves and blood vessels for the nourishment of the teeth. 

The teeth are held firm in their alveolar sockets by a union called 
gomphosis, which resembles the attachment of a nail in a board. Teeth 
with one conical root and those with two or more perpendicular roots, are 
retained in position by an exact adaptation of the tissues. Teeth having 
more than one root, and those bent or irregular, receive support from all 
sides by reason of their irregularity. The teeth are also held in position 
by the peridental membrane. In Fig. 164 is seen the position of the teeth 




Figure 164 
Superior and inferior maxillary bones and teeth with the outer plate of alveolar process re- 
moved (original). 

in the jaws. The peridental membrane lining the alveolus and covering 
the roots of the teeth is a fibrous tissue, which admits of slight motion of 
the teeth and acts as a cushion to protect the jaws from severe blows and 
concussion while tearing and grinding food. If, for any reason, the teeth 
do not erupt, the alveolar process is not present. On the other hand, when 
extraction is necessary or if the teeth drop out on account of interstitial 
gingivitis, the alveolar process absorbs (Fig. 165). 

When teeth are moved for the purpose of correcting irregularities, 
the alveolar process will absorb on the one hand, and build itself around 
the tooth in its new position, at any period in the development of the grow- 
ing child. When, however, the child has obtained its growth, because of 
its transitory nature and because of the fact that the alveolar process has 
completed its function, new bone rarely is deposited about the roots of 
the teeth. 



A STUDY IN DEGENERATIVE EVOLUTION 



227 



So rapid is the tendency of the alveolar process to develop between 
the sixth and twelfth year (the second and third periods of stress) that not 
infrequently when teeth are misplaced they can be directed to their normal 




Figure 165 Figure 166 

Superior and inferior maxillary bone. Absorption Enlargement of the anterior superior alveo- 

of the alveolar process where the teeth have lar process influenced by the lower teeth 
been removed (original). (original). 

position by slight mechanical assistance. The crowns of the teeth them- 
selves, while erupting, wedge their way into position and with the help of 
the developing bones enlarge the dental arch (Fig. 166). No matter what 
position the permanent teeth may take the alveolar process, being a transi- 
tory structure and only intended to hold the teeth in place, moulds itself 
about the roots of the teeth. 

There are from twenty-eight to thirty-two foreign bodies (teeth) set 
on end in a vascular, transitory, bony structure (the alveolar process). 
Children with unstable nervous systems, not infrequently have an extra 
deposition of calcium salts in the alveolar process which causes the bone 
to become very dense and hard. This may occur in the entire length of 
the alveolar process or only one side may be involved; again, only the space 
in which one, two or three teeth may be located. This excessive deposition 
of bone cells in the alveolar process may occur at the eruption of the 
temporary as well as of the permanent teeth. An excellent illustration 
of this developmental pathologic condition is seen in the late eruption of 
the temporary and permanent teeth. The bone becomes so dense that 
sometimes the incisors do not make their appearance for a year, and some- 
times much later. 

Deposition of Salts. Excessive deposition of bone salts is again 



228 



DEVELOPMENTAL PATHOLOGY 



illustrated in the alveolar process at the points of eruption of the premolars. 
Not infrequently these premolars are not shed, and the alveolar process 
does not expand in harmony with the bone, the permanent molars and the 
six anterior teeth. As a result the crowns of the bicuspids are held between 
the roots of the temporary molars, which, when developed, occupy a 
smaller circle than the permanent teeth. It is this late eruption of the 
bicuspids that most largely assists in the formation of the saddle-shaped 
arch. We observe this dense bone structure in connection with the erup- 
tion of the incisors of the second set of teeth. Not infrequently, after 
the roots have become absorbed and the temporary teeth removed, bone 
cells are so densely deposited over the crowns of the permanent teeth that 
it is with difficulty they can bring about the absorption of the alveolar 
process necessary for their appearance. Again, the density of bone about 
the roots of teeth may cause slow eruption of the permanent teeth; or the 
bone may become so dense that the teeth can hardly push their way into 
the mouth, so that the alveolar process will barely expose the entire crowns 
of the teeth. 

Injuries to the temporary teeth, such as blows, will cause a deposition 
of bone cells about the roots, thus retarding the eruption of the permanent 
teeth. On the other hand, injuries and alveolar abscesses to the first teeth 
frequently cause interstitial gingivitis and bone absorption, exposing the 
crowns of the permanent teeth. 

The irritation produced by the eruption of the teeth in those children 
possessing an unstable nervous system may be so great as to cause hyper- 
trophy of the alveolar process. This may not be apparent upon observa- 




FlGURE 167 

Hypertrophy of the superior alveolar process 
throughout (original). 



Figure 168 
Hypertrophy of the alveolar process through- 
out (original). The right alveolar process 
because of the hypertrophy has carried the 
teeth out of position. 



A STUDY IN DEGENERATIVE EVOLUTION 229 

tion, yet the bone in its arrested form may not expand sufficiently for all 
the permanent teeth to come into place. Not infrequently, in more 
markedly degenerate children, there will be no room for the cuspids, which 
may or may not erupt outside of the dental arch. In more profound 
degeneracies, hypertrophy, owing to an unstable nervous system and to 
the local irritation of erupting teeth, may be in evidence (Fig. 167). In 
this particular instance, many of the points previously mentioned are 
noticeable. The jaw has not developed; the teeth are only partially 
erupted; while the cuspids are outside of the dental arch. Fig. 168 shows 
hypertrophy of the alveolar process to such a degree that the vault is almost 
obliterated. The teeth were slow in erupting and the expansion of the 
arch was impossible. Fig. 169 shows an arrest of development of the 




Figure 169 
Hypertrophy of the alveolar process in connection with three left superior molars (original). 

entire bone, with a V-shaped arch on one side and a semi-V and semi-saddle 
shaped arch on the other, and hypertrophy of the alveolar process which 
has prevented the molars from erupting. 

With such a picture in view, I can but condemn the vicious practice 
of undertaking to correct like irregularities by means of pressure, in this 
unstable type of children, a measure which must be accomplished at or 
about the third period of stress. How much more to be condemned is 
the practice of trying to expand the arch without extraction. 

Microscopic Aspects. Having considered the alveolar process in 
its gross aspects, its microscopic aspect will now be studied. 

Under the microscope, two systems of Haversian canals are seen in 



230 



DEVELOPMENTAL PATHOLOGY 



the alveolar process. These Haversian canals, according to Kolliker, are 
of two kinds. One, with the regular lamellae system surrounding it, and 
the other, the so-called Volkmann's canals, containing the perforating 
vessels of Von Ebner, which have no surrounding lamellae, but simply 
penetrate through the layers of bone. Volkmann's canals are present in 
all tubular bones in old and young. While especially marked in the outer 
basal lamellae, they occur also in the interstitial leaflets and in the inner 
chief lamellae as well as in the periosteal layers of the skull bone. Here 
their number is variable. They run partly transversely or obliquely, and 
partly longitudinally through the lamellae. Many of these canals open 
in the outer or inner surfaces of the substantia (compact substance) and 
also here and there in the Haversian canals, and usually form altogether a 
wide-meshed irregular net-work. In structure they are sometimes smooth 
and sometimes furnished with dilatations and angles projecting in and out 
in profile. The widest has a diameter of 100 micrometers or more, the 
narrowest not more than 10 or 20 micrometers, and there are still narrower 
ones which are altogether obliterated, appearing like rings or circularly 
formed structures without any lumen, or like those far from rare obliterated 
true Haversian canals first described by Tomes and de Morgan. The 
contents of the Volkmann canal are the same as the Haversian canal. 





~ : ~ "■::'. " ".. --^v. 



^Ctf 







Figure 170 Figure 171 

Microscopic section of bone showing blood Section of bone (higher magnification) show- 
vessels of Von Ebner (Kolliker). ing blood vessels of Von Ebner (Kolliker). 



A STUDY IN DEGENERATIVE EVOLUTION 



231 



Fig. 170 is a cross section of the medulla of a calcified human humerus, 
slightly enlarged. The outer lamellae contain a large number of Volk- 
mann's canals running longitudinally and transversely and extending 
through the outer plate of bone into the periosteum. Fig. 171, the cross 
section of the section seen in Fig. 170, shows these canals more highly 
magnified. The Haversian canals are large round spaces, Fig. 172 con- 




FlGURE 172 

Transverse section of the humerus magnified 

350 times (Gray). 



Figure 173 

Longitudinal section of bone magnified 100 

times (Gray). 



taining a single artery and vein. The fine hair-like spaces running from 
these large spaces are canaliculi. The dark spots encirling each Haversian 
canal are the lacunae. The canaliculi run from one lacuna to another, or 
into an Haversian canal, or anastomose with each other. The lacunae seem 
to be about uniformly distributed throughout the bone. The spaces 
between the lacunae and canaliculi are filled with lime salts. 

A longitudinal section of bone (Fig. 173) is similar in appearance to 
the cross section. Instead of the lacunae being arranged in rows around 
the Haversian canals, they are parallel. It will be noticed that the Haver- 



232 DEVELOPMENTAL PATHOLOGY 

sian canals run in different directions and communicate with each other 
at certain intervals. The foregoing covers essentially the minute anatomy 
of the alveolar process. 

Summary 

The alveolar processes are distinct and separate structures from the 
maxillary bones, being transitory, provisional bones. 

They do not appear until the first teeth are erupted, moulding them- 
selves around the roots. 

The process consists of an outer and inner plate, joined at intervals 
by calcellous septa, the inner being the thicker, because the absorption of 
the process is slower than the growth of the jaw. 

As the jaws grow smaller in evolution, the teeth grow smaller in 
diameter and longer in root, producing a higher arch. 

The teeth are fixed in their alveolar sockets by gomphosis, resembling 
a nail in a board of wood. 

The teeth act as foreign bodies to the alveolar process, rendering the 
latter physiologic end-organs. 

Under the influence of an unstable nervous system, or trauma, or 
inflammation, an extra deposition of calcium salts occurs, making the 
bone dense and hard, retarding, in children, the eruption of the second 
teeth. 

Or, under similar influences, the alveolar process may hypertrophy, 
crowding out some of the teeth and narrowing the arch. 

Correction by pressure, under these circumstances, is to be condemned, 
also attempts to widen the arch without extraction. 

Microscopically, the alveolar process contains two types of Haversian 
canals — (1) with regular lamellae systems surrounding it, (2) the so-called 
Volkmann's canals, containing the perforating vessels of Von Ebner and 
no surrounding lamellae. 



Chapter XX 
INTERSTITIAL GINGIVITIS 

IT is necessary now to consider developmental pathology of the alveolar 
process. In the evolution of the head, face, jaws and teeth, the 
alveolar process, including the jaws, grows smaller and the alveolar 
process changes its shape. It, therefore, must be considered a transitory 
structure. In the preceding chapter it was shown that the alveolar process 
is a bony structure intended only for the purpose of holding the teeth in 
position. This bony structure is absorbed when the teeth are removed 
and is therefore a transitory structure. In phylogeny, all vertebrates 
which have teeth, namely, fish, batrachians, reptiles and mammals, shed 
their teeth in some manner. 

In Some Fish the teeth are constantly shed and renewed during the 
whole course of their lives. In fish which have compound teeth, as well 
as in those which have apparently permanent teeth, as in the saw of the 
sawfish, the wear of the surface is made up by a constant growing of the 
tooth from its base. When the teeth are implanted in the alveoli, they 
are generally succeeded by others in the vertical direction, as in Sargus, 
but in others they succeed one another, side by side, as in sharks, rays 
and skates. Generally, there are more than one tooth growing which are 
in various stages of development, and destined to replace the one in func- 
tion. 

In the Manatee the incisors are rudimentary, concealed beneath 
the horny oral plate and disappearing before maturity. Molars ll/ll 
but rarely more than 6/6 present at one time. These teeth succeed each 
other from before backwards, as in the elephant, the anterior teeth falling 
before the posterior teeth come into use. 

In the Dugong besides the large tusk-like incisors, there is, in the 
young, a second small deciduous incisor on each side above. At this age 
there are also beneath the horny plate which covers the anterior portion 
of the mandible four pairs of slender teeth in wide alveolar depressions; 
these become absorbed before the animal reaches maturity. The molars 
are usually 5/5, sometimes 6/6 altogether, but not all in place at once, as 
the first falls before the last rises above the gums. 

In Snakes there is a perpetual succession of teeth. This holds good 
for reptiles and all amphibians that have teeth. 

In Crocodiles as the teeth wear out or are lost they are replaced by 
others, formed on the inner side of those which they are destined to succeed. 
This process appears to go on indefinitely throughout life. 

233 



234 DEVELOPMENTAL PATHOLOGY 

In Elephants six teeth are successively developed, the hinder-most 
one being much more complex than the anterior ones. 

In Man's Ontogeny it would be strange if he did not retain some of 
the phylogenetic peculiarities of the lower vertebrates in tooth develop- 
ment in relation to the alveolar process. Man has two sets of teeth. He 
sheds the first after it has performed its function, and a new set takes its 
place. As soon as the alveolar process has developed about the teeth, and 
man has attained his growth, a low form of inflammation is present to set 
up absorption. I have called this process osteomalacia, or senile absorp- 
tion. This form of absorption will continue until the teeth loosen and 
drop out if man lives long enough and continues in a fairly normal state of 
health. This process is atavistic. In this respect, also, we have a transi- 
tory structure. The alveolar process, therefore, may be considered a 
doubly transitory structure. 

The Alveolar Process as an End Organ. I have called the alveo- 
ar process an end organ. My reason for doing this is that the tooth, so 
far as the process is concerned, is a foreign body. The arteries, vessels of 
Von Ebner and especially the nerves pass through the bony process, in a 
wavy manner and stop at the root of the tooth. 

There are other end organs in the body, chief of which are the kidneys, 
the eye and the brain. Physicians claim, and rightly, that because these 
are end organs they are more easily involved in disease and are often the 
determining factors of kidney lesions. Alfred C. Croftan says, "It is not 
surprising to find that particularly those organs that are supplied by end 
arteries are chiefly involved, for in them vascular disturbances must first 
produce nutritional derangement. Chief among the organs supplied by 
end arteries are, precisely, the kidneys, the retina and the brain, and I 
think this explains the frequent involvement of the kidneys, eyes and brain 
in Bright 's disease. The fact that the retina and the brain are often found 
injured before the kidneys, that cases of Bright 's disease run their fatal 
course occasionally with practically no renal changes, but with serious 
apoplectiform brain lesions and retinitis, bears out this conception and 
constitutes a valid argument against the common belief that the nephritis 
is the primary event and the determining phenomenon of the disease." 

A marked difference exists between the kidney, eye and brain as end 
organs and the alveolar process as an end organ. This difference is the 
important point in the study of interstitial gingivitis. End arteries running 
into the kidney, eye and brain, owing to the soft nature of these tissues, 
are given a chance to expand and recover, permitting, in a measure, the 
blood to flow more easily, thus prolonging the tendency to disease, or 
allowing the tissues, under favorable conditions to recover. On the other 
hand, blood vessels extending throughout the alveolar process in a tortuous 



A STUDY IX DEGENERATIVE EVOLUTION 235 

manner cannot expand, and as a result, blood charged with toxins and 
subject to cardio-vascular changes immediately sets up irritation and 
inflammation which results in dilatation, bone absorption and arterial 
degeneration. These changes, therefore, will occur much earlier in the 
alveolar process than in other end organs. 

The transitory nature of the alveolar process, especially as an end 
organ, makes it exceedingly sensitive to systemic changes and disease. 
The sensitiveness of this structure to autotoxic states is easily demonstrated 
as people advance in years. At the fifth period of stress fabout forty-five; 
the excretory organs weaken. The toxic elements of the body are not 
carried off as freely as formerly. These circulate in the blood and accumu- 
late in the alveolar process, setting up irritation and inflammation. Ab- 
sorption of the alveolar process gradually takes place. People enjoying 
apparently good health will, as they advance in years, note the absorption 
of the alveolar process and the exposure of the roots of the teeth. How 
much more readily will absorption take place when the function of any 
one of the eliminating organs be involved, such as constipation, asthma, 
skin affections or kidney lesions. 

Causes of Interstitial Gixgtvitis. Diseases which attack the 
alveolar process and cause interstitial gingivitis may be classified under 
two heads. First, infectious diseases, such as syphilis, tuberculosis, acti- 
nomycosis, anthrax, spirilla and gonococci, etc. Second, irritations, those 
of a local and constitutional nature. Infectious diseases, as compared 
with those due to local and constitutional irritation, are not so common. 
Each infection, however, possesses its own characteristic picture and can- 
not be confused with the irritations or with other infections. 

The Irritations of a Local Nature which produce interstitial 
gingivitis are, the eruption of the teeth; the movement of the teeth by 
mechanical appliances for the purpose of correcting irregularities, for 
acquiring space for filling teeth, crown and bridgework; ill-fitting artificial 
dentures; heat under artificial dentures; ragged edges of fillings; collections 
of food and other foreign material such as tartar, calcic deposits, etc.; 
excessive use of brushes; toothpicks and all other local irritations. 

The Constitutional Irritations are drug and metal poison and 
autointoxication, due to disease and faulty metabolism. 

The bone, at the gingival border, is usually the first involved because 
it is thinner and because it is farthest remote in artery and nerve supply, 
and gradual absorption takes place toward the end of the root. This, 
however, is not always the case. Occasionally, the irritation is located 
in the bone at the middle or apical end of the root causing interstitial 
gingivitis and absorption of bone at these localities. These irritations 
may be caused by gases passing out of the root at the apical end, due to a 



236 DEVELOPMENTAL PATHOLOGY 

dead pulp or to an accumulation of toxins in the blood, following the 
arteries in these localities and other causes. 

Scurvy produces the same train of symptoms as the metals, through 
its disturbance of metabolism. 

The Jaws of the Hereditarily Defective, whether the defect be 
in the direction of advance or degeneracy, are fruitful soil for the develop- 
ment of interstitial gingivitis. In the mouths of the congenital deaf, 
dumb, blind, feeble-minded and delinquent children, interstitial gingivitis 
attacks the alveolar process before the osseous system has reached its 
growth. Here, as a consequence of trophic change, metabolic action and 
premature senility, interstitial gingivitis may occur in connection with 
the first set of teeth at two years or any period thereafter. This may be 
called juvenile interstitial gingivitis. Regulating teeth and senile absorp- 
tion are predisposing causes to future interstitial gingivitis. 

Interstitial Gingivitis in Animals. Interstitial gingivitis of the 
alveolar process is almost as common among domestic and wild animals 
in captivity as it is in man. Wild animals in zoologic gardens without 
proper exercise, in close confinement, with impure air, and fed upon too 
easily digested food, naturally acquire autointoxication, resulting in inter- 
stitial^ gingivitis. This is particularly noticeable in monkeys, whose 




Figure 174 
A monkey skull showing absorption of the alveolar process (original) . The right central and 
left lateral have dropped out. The alveolar process is absorbed so that all teeth are 
loose. 



A STUDY IN DEGENERATIVE EVOLUTION 



237 



changes of environment render them very susceptible to disease, especially 
to tuberculosis. Trophic changes and impaired metabolism are thereby 
so impressed upon monkeys that not infrequently the first teeth become 
prematurely loose and drop out. Fig. 174 is the skull of a monkey who 
died, aged one year, of tuberculosis. Absorption of the alveolar process is 
the result of tubercular autointoxication. The right superior and inferior 
central and lateral incisors have loosened and dropped out. The roots of 
all the teeth are exposed to a marked extent. The teeth could be removed 
with the fingers. 




Figure 175 

The mouth of a Scotch terrier (original). All the teeth on the right side, posterior to the 

cuspids have dropped out. The other teeth are loose. 



238 DEVELOPMENTAL PATHOLOGY 

The horse and cow are prone to this disease. Cattle return to the 
stable after the summer's sojourn in the field and then, being fed upon a 
changed diet without the usual exercise of cutting grass with their teeth, 
undergo a reaction in their jaws and interstitial gingivitis results. "Crib- 
bing" of the horse is a marked illustration of the uneasy feeling resultant 
on this reaction. Cattle fed upon brewers' grain and slops suffer most. 

Dogs afford the best opportunity, however, for studying interstitial 
gingivitis among animals. An examination of dogs in one hospital showed 
that every one had interstitial gingivitis in all degrees from its inception 
to the loss of all the teeth. The number of dogs observed was twenty- 
seven. The outer plate of bone was absorbed, the roots entirely exposed, 
pus was oozing from around them and the mucous membrane was badly 
inflamed. It should be remembered that the jaw of the dog, like the jaw 
of man, is undergoing considerable variation. Like man, the dog, having 
put himself under new social conditions, so to speak, is varying greatly 
both as to brain, skull and jaw from his wolf -like ancestor. As he is under 
the protection of man, the struggle for existence is less intense than in the 
wild state, and consequently, there is less occasion, even for fighting pur- 
poses, for the use of his jaws and teeth. Independently of conditions of 
this type, many of the dogs suffered from constitutional disorders. Eight 
had skin diseases which, in the dog, are more likely to produce obvious 
constitutional defects than in man. Some were old and blind. Some 
had been injured and were under treatment for wounds; some were suffer- 
ing from rachitis, nervous diseases, and were over-bred. Others were 
constipated, or had germ type diarrhoea. One had kidney inflammation 
and bronchitis with high fever. In short, these dogs, being house dogs, 
presented most of the constitutional diseases to which man is liable. 

The mouth of a Scotch terrier is shown in Fig. 175. The teeth on the 
upper and lower jaw had been removed with the fingers from the cuspids 
back. The cuspids and incisors were quite loose. There are large deposits 
of tartar. The gums and alveolar process have been absorbed nearly one 
half the length of the roots of the remaining teeth. Fig. 176 shows the teeth 



ftl?&ft*Jft 



Figure 176 
Teeth of dog removed by fingers due to interstitial gingivitis (original). 



A STUDY IN DEGENERATIVE EVOLUTION 239 

covered with calcic deposits the entire length of the root which I removed 
from the mouth of another dog. These teeth were removed by the fingers 
from a dog obtained for scientific study. 

Twenty-five per cent of roving dogs at four years of age have the 
disease. Eighty per cent of eight-year-old, at least ninety-five per cent 
of twelve-year-old and all fourteen-year-old dogs have the disease. House 
dogs suffer to a marked extent with interstitial gingivitis of the alveolar 
process, no doubt from being trained to house cleanliness which interferes 
with natural excretion, causing autointoxication and odor. 

Fig. 177 is that of a physician thirty-six years of age. Fig. 178 is that 
of a physician thirty-eight years of age. Both these gentlemen are appar. 




Figure 177 Figure 178 

Cast showing absorption of the alveolar process Cast showing absorption of the alveolar process 

due to interstitial gingivitis (original). due to interstitial gingivitis (original). 

ently in the best of health. One has slight indigestion, which is the cause 
of absorption; the other took calomel for malaria, fifteen years previous, 
and became salivated. This is a predisposing cause. In each case, all 
the teeth are involved both inside and out, some are loose. There is no 
pus in either case and the gums are apparently healthy. 

In consulting the literature upon this subject, I find that absorption 
of the alveolar process and recession of the gums has been attributed, by 
many authors, to the severe use of the tooth brush. There are certain 
conditions in which the tooth brush will assist absorption of the alveolar 
process. These are easily observed. I refer to the position of the cuspid 
teeth, where they stand prominently. The bone over the roots of the 
teeth in these instances is as thin as tissue paper, and the slightest friction 



240 



DEVELOPMENTAL PATHOLOGY 



will set up a low form of inflammation, which, in turn, produces absorption 
of the bone, exposing the root. The brush never, however, produces 
senile atrophy in other parts of the mouth except under similar conditions. 

The absorption of the alveolar process in interstitial gingivitis is not 
always uniform, as sometimes only one or two teeth are involved. Local 
conditions, however, modify the extent of the disease. In most instances, 
there is a gradual absorption of bone about all the teeth. 

The pathology of interstitial gingivitis is not unlike osteomalacia of 
the pelvis, spine or other bones of the body, as demonstrated by Hektoen. 
Halisteresis is the principal form of absorption. Perforating canal absorp- 
tion, described by Volkmann, is common, passing through fragments of 
bone. Lacunar absorption is also present and osteoclasts are frequently 
found. Howship's lacunae containing osteoclasts are found in the margin 
of irregular islands of bone. This form of absorption, while nearly always 
present, is not so important as halisteresis, being much slower in its action. 
New osteoid tissue is rarely seen. This absorption is a natural destruction 
and the bone is never reproduced. 




Figure 179 
Microscopic illustration of the first stage of inflammation in jaw of dog (original). Shows 

thickening of arteries. 



A STUDY IN DEGENERATIVE EVOLUTION 



241 



To demonstrate the effect of drug poisons and other irritants upon 
the alveolar process, a series of experiments have been conducted for two 
decades on animals and human. These consisted of the examination of 
the jaws of dogs with interstitial gingivitis due to different diseases; to 
saturating the system of healthy dogs with mercury; the examination of 
the jaws of monkeys who died of tuberculosis; the examination of the 
jaws of cows and horses suffering with interstitial gingivitis due to faulty 
metabolism; and the examination of human jaws with diseases resultant 
from tuberculosis, syphilis, mercury and lead poisoning and scurvy. A 
series of experiments were conducted, extending over one winter, on dogs 
whose teeth I moved in an analogous manner to the correction of irregulari- 
ties of the teeth in the human. The structures were removed and prepared 
in the usual way for the microscope. 

Fig. 179 shows round cell infiltration and inflammation extending to 
the inner coat of the blood vessel, and also plasma mass cells. This in- 
flammatory process was brought about at the gingival border of the alveo- 
lar process by administering mercury to a young, healthy dog. This 
illustration shows the first stage of the inflammatory process. Quite a 
thickening of the arterial wall is observed. 

The following illustration (Fig. 180) represents the alveolar process 
of a man forty-eight years of age, killed in an accident. The illustration 




Figure 180 
Four centers of halisteresis absorption beginning at Haversian canals in alveolar process of 

man (original). 



242 



DEVELOPMENTAL PATHOLOGY 



shows four areas of bone absorption called halisteresis (melting away of 
bone substance). The waste products become irritants in the blood 
stream and set up a low form of inflammation in the Haversian canals. 
The inflammation thus set up produces rapid absorption. Each of these 
local areas enlarges until they join. In this way, large areas of absorbed 
bone are produced. In the center of this illustration is seen an Haversian 
canal with active inflammation around it. The bone is absorbed. The 
inflammatory process is in the trabeculae or fibrous part of the bone. 
Adjoining is a large area with bone absorption, but the fibrous part of 
bone remains unbroken. The inflammatory process is seen throughout. 
At the lower border of the picture are two large areas of bone absorption. 
The trabeculae are seen with round-celled infiltration, while the center is 
destroyed. At the right, absorption and destruction of the trabeculae 
are seen to the margin of the bone. 

Fig. 181 shows halisteresis at two Haversian canals. One area is 
much larger than the other. Both have met and the area of inflammation 




Figure 181. 
Two areas of halisteresis absorption showing trabeculae with round cell inflammation 

(original) . 

will be much enlarged. The trabeculae are present and filled with round- 
celled infiltration. 

Fig. 182 illustrates a large area of absorption, with destruction of the 
fibrous tissue to a larger extent. Around the border is seen a small amount 
of inflamed fibrous tissue. An artery, once an Haversian canal, is also 
seen. About the large area are also seen three Haversian canals with the 
inflammatory process just beginning. 



A STUDY IN DEGENERATIVE EVOLUTION 



243 





r 




1 




v 

• * 

■ 




It • 








* 


* 




• .■'■& .-. 



Figure 182 
Three areas of inflammation at Haversian canals (original) . In the lower and larger area, the 
trabeculae have been destroyed; only a slight amount with round cell infiltration is 
noticed at the border. When the trabeculae is destroyed in large areas, the bone is 
never reproduced. 




Figure 183 
Shows four areas of halisteresis absorption with Volkmann canal absorption proceeding 

between the area (original) . 



244 



DEVELOPMENTAL PATHOLOGY 




//o.7 



Figure 184 
Lacunar or osteoclast absorption of the alveolar process (original) . 



mm 






/fo.S. 









Figure 185 
Three forms of bone absorption between bicuspid roots (original). 



A STUDY IN DEGENERATIVE EVOLUTION 



245 



Fig. 183 shows four centers of absorption at Haversian canals. Through 
the picture may be seen dark lines running in all directions. These are 
vessels of Von Ebner, through which Volkmann's canal absorption takes 
place. A beautiful illustration of this is seen in the canal running from 
one large area of absorption to the other. 

Fig. 184 shows the third form of bone absorption — lacunae or osteoclast 
absorption. Here a large area of bone is destroyed by these large cells. 

Fig. 185 is a" low power, showing the distribution of the alveolar 
process between the roots of two teeth. Very little of the bone remains. 
When the trabeculae or fibrous tissue is destroyed in large areas, and 
especially in transitory structures, it is rarely restored. 

In the different forms of bone absorption, especially halisteresis and 
Volkmann's perforating canal absorption, islands of bone are seen in the 
fibrous remains of the alveolar process (Fig. 186 and 187). These spiculae 




Figure 186 

Islands of alveolar process in dog due to two forms of bone absorption (original) . J, island of 

alveolar process; o, lacunar absorption; i, halisteresis absorption with trabeculae in position. 



246 



DEVELOPMENTAL PATHOLOGY 



of bone are sometimes very annoying and cause considerable trouble. 
Occasionally, they produce so much irritation that an abscess will form, 
discharging the piece of bone through a fistulous opening. Again, the 
bone will become exfoliated by means of absorption, without abscess. 

In the earlier symptoms of interstitial gingivitis, erosion, abrasion, 
discoloration and tooth softening, due to faulty metabolism and autointox- 




FlGURE 187 

Cross section of tooth alveolar process and peridental membrane in man (original), d, dentin; 
c, cementum; i, peridental membrane and trabeculae; j, island of aveolar process; o, 
lacunar absorption. 

ication, there are no symptoms of blood pressure. The transitory nature 
of the alveolar process and tooth pulp, both being end organs, make them 
more susceptible to blood changes than other structures of the body. 
These tissues, therefore, may become diseased for many years before other 
structures of the body become involved. Later, however, when the 



A STUDY IN DEGENERATIVE EVOLUTION 247 

more serious symptoms result, such as renal insufficiency, acute and 
chronic nephritis and changes in heart and arteries, blood pressure is 
observed. 

To ascertain the blood pressure in patients suffering with interstitial 
gingivitis, I used Cook's modification of the Riva Rocci Sphygonomano- 
meter, this instrument being best adapted for my convenience and exceed- 
ingly simple. The patients ranged from twenty-seven to sixty-seven 
years of age. With this instrument, the normal adult female arterial 
blood pressure is 115 to 125 mm.; adult male, 125 to 135 mm. 

In twenty-six females there were three who ranged between 115 mm. 
Hg. and 125 mm. Hg. and, therefore, normal. Three ranged below 115 
mm. Hg. and twenty from 133 mm. Hg. to 180 mm. Hg. 

In twenty-four males there were eight who ranged between 125 mm. 
Hg. and 135 mm. Hg. and, therefore, normal. Three ranged below 125 mm. 
Hg., and thirteen from 133 mm. Hg. and 160 mm. Hg. 

When we consider that thirteen of these patients were under forty- 
five years of age, the high blood pressure is remarkable. 

I have been unable to demonstrate whether the interstitial gingivitis 
is accelerated directly because of the poisons circulating in the blood 
vessels, causing high blood pressure by their action upon the heart, or 
because of their action upon the vasomotor nerve governing the heart or 
blood vessels, or both. 

Summary 

All phylogenetic types of vertebrates shed their teeth in some manner 
and renew them — the lower types more or less continuously throughout 
life. 

Man sheds his first (temporary) set and develops his second (perma- 
nent) teeth. 

As soon as these are developed, an inflammatory process sets in around 
the roots, called by the author osteomalacia, which will eventually loosen 
the teeth and allow them to drop out. In this respect, the alveolar process 
is a doubly transitory structure. 

The alveolar process is an end organ similar to the eyes, brain and 
kidneys, but with this important difference, that its substance is hard, 
allowing no expansion of terminal arteries, and making the alveolar process 
peculiarly sensitive to change and disease, which bring about an inflamma- 
tion-absorption process known as interstitial gingivitis. 

Causes may be classified into infections and irritations, each mani- 
festing its own symptom — complex. 

In hereditarily defective children the absorption begins before ossifica- 



I 

248 DEVELOPMENTAL PATHOLOGY 

tion, thus producing interstitial gingivitis of temporary teeth — juvenile 
gingivitis. 

Domestic and caged animals suffer from gingivitis. 

The pathology consists chiefly of halisteresis, also of Volkmann's 
perforating absorption. 



Chapter XXI 
ENDARTERITIS OBLITERANS AND CALCIC DEPOSITS 

ONE of the most interesting pathologic processes which almost always 
develops in connection with interstitial gingivitis is that of endar- 
teritis obliterans. The alveolar process, being a doubly transitory 
structure and an end organ, the arteries in their tortuous position are 
unusually susceptible to this disease. The poisons circulate in the blood, 
accumulate and set up irritation and inflammation of the coats of the 
vessels which become thickened and obliterated. 

Pathology. Endarteritis is an inflammation of the intima or internal 
coat of the arteries, generally of a chronic type. Other coats of the arteries 
may become involved and also show a thickening. Its pathogeny is as 
follows: In direct contact with the blood streams is the endothelium (a 
layer of flattened cells); next is the tunica intima, composed of elastic 
fibers arranged longitudinally; next comes the middle coat, composed of 
muscular fibers arranged transversely. The outer coat consists of longi- 
tudinal connective tissue, which contains the vasa vasorum. In the 
capillaries the intima lies in immediate contact with the surrounding 
tissues, or is accompanied by a rudimentary adventitia. In other words, 
the walls of the capillaries consist of almost nothing but the intima. The 
capillaries have a certain contractility; they contract or dilate without 
muscular fibers. The veins probably also exhibit a certain amount of 
contraction and dilation from irritability of the intima. Each coat of the 
arteries takes on a special type of inflammation. 

The causes of endarteritis are numerous. Inflammation of the intima 
of the blood vessels may be due to irritation from without or within. When 
it occurs from without, any local irritation will set up an inflammation 
which may extend to the outer coats of the capillaries. This produces a 
marked increase of blood. The vasa vasorum become swollen, the white 
blood corpuscles crowd into the terminal capillaries and migrate into the 
extra vascular space. Rapid proliferation of the round cell elements takes 
place. The walls of the vessels become thickened. Owing to the project- 
ing intervals of the intima, the caliber of the blood vessels diminishes 
(Fig. 188). 

Causes. Irritation occurring from within results either from trophic 
changes in the system or from direct irritation from toxemias, or may 
come from both interdependently. Under these circumstances a germ 
disease or other toxins may have an affinity for a certain organ, tissue or 
part, and produce irritation in the capillaries in a distinct part of the body; 
or the capillaries through the entire body may become involved. Thus, 

249 



250 DEVELOPMENTAL PATHOLOGY 

in typhoid fever, Peyer's glands in the intestine become involved; in scarlet 
fever, the skin or kidney; in malaria, the liver and spleen; in Bright 's 
disease, the kidney; while in mercurial and lead poisoning and scurvy, 
the mucous membrane and especially the gums become diseased. In 
many of these conditions, however, before the tissue already irritated 



Figure 188 

Endarteritis obliterans (Kaufman). A, adventitia; e, elastic tissue between middle coat and 

intima; m, muscular; j, thickened intima. 

becomes involved, the nervous system may already have become affected 
from other causes, such as locomotor ataxia, traumatic injuries to the spine, 
paretic dementia, cerebral paralysis, neuroticism and degeneracy, and 
last but not least, stomach neurasthenia. The poison in the blood, to- 
gether with the diseased peripheral nerves . produces irritation and inflam- 
mation of the inner coat of the capillaries. If this irritation does not 
disappear soon after its inception, the inflammation tends to affect the 
other coats of the blood vessels. Under certain conditions, however, 
endarteritis may never involve the other coats of the vessels. When 
irritation of the inner coat of the capillaries takes place proliferation of 
the endothelium occurs. This inflammatory growth tends to obstruct 
the lumen of the vessel. The media may likewise become thickened by an 
increased connective tissue. The capillaries become obstructed and 
finally obliterated, which eventually impedes the circulation. Fig. 189 
shows such a condition in a case of scurvy. 

Irritation may be of less intensity but greater duration, as in syphilis, 
tuberculosis, scurvy, mercurialism, plumbism, etc., and the results are 
then effected slowly. Proliferation of subendothelial connective tissue 
gradually increases until it reaches its limit (endarteritis obliterans) . This 
influence of the proliferation is exerted in addition to that of the round- 
cell infiltration about the structure. 

The recent studies of Hektoen on meningeal tuberculosis demonstrate 
that tubercle bacilli may penetrate the unbroken endothelial layers of the 
vessel and stimulate proliferation of the subendothelial connective tissue. 
An internal irritant, such as may be produced in the course of any infectious 



A STUDY IN DEGENERATIVE EVOLUTION 



251 



disease or from sulfoxidation, probably acts upon the endothelium of the 
walls of the smaller blood vessels in such a way as to permit the escape 
through the walls, first of serum, and then of leucocytes, the latter infecting 
and surrounding the vessels. The effect of the chronic endarteritis is to 




Figure 189 

Endarteritis obliterans. Scurvy in man (original). C, cementum; d, dentin; i, peridental 

membrane; u, nerve tissue; eo, endarteritis obliterans. 



check the blood supply to the gum and alveolar tissue. Mercury, lead 
and other poisons circulating through the blood are forced to remain, hence 
the discoloration of tissue along the gum margin. Interstitial gingivitis, 
resulting in a slow disturbance of nutrition, produces overgrowth of con- 
nective tissue. In all cases of chronic interstitial gingivitis, as shown in 
the illustration, are the blood vessels thus involved. 

Among the predisposing influences which cause this disease are syphi- 
lis, tuberculosis, mercurialism, plumbism, brass poisoning, lithemia, 
nephritis, gout, rheumatism, alcoholism, scurvy, nervous diseases, preg- 
nancy and old age. Under certain conditions of the system any and all 
diseases which tend to lower the vitality, producing anaemia, will assist in 
producing this disease. The direct cause may be resultant overstrain of 
the blood vessels. 



252 



DEVELOPMENTAL PATHOLOGY 



On administration of drugs, especially mercury or lead, to healthy 
young dogs, inflammation of the alveolar process with diseased arterial 




Figure 190 
Endarteritis obliterans in pregnancy (original). The two light spots are centers of arteries 

nearly obliterated. 



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Figure 191 

Endarteritisobliterans in alveolar process of dog (original), n, trabeculae remaining after 
absorption of bone; eo, endarteritis obliterans. 



A STUDY IN DEGENERATIVE EVOLUTION 



253 



walls is seen at the end of a month or six weeks. Fig. 179 shows the 
commencement of the thickening of the intima in a dog. The coats of 
the arteries are well defined, and the inflammatory process has just begun. 
Examination of the alveolar process of animals or human beings suffering 
from disease in which the eliminating organs are not throwing off effete 
matter, especially in syphilitic, tuberculous and scorbutic patients, easily 
reveals this morbid state. 

Fig. 190 is a poor illustration of the disease in pregnancy. If such 
patients are degenerates the process will be exaggerated. 






Figure 192 
Endarteritis obliterans in a tuberculous monkey (original). At the left may bejseen an 
artery cut lengthwise almost obliterated. In the center an artery cut crosswise almost 
obliterated. Just below are two small obliterated arteries. At the right lower corner 
may be seen a large obliterated artery. In this picture the bone has entirely absorbed 
leaving the trabeculae intact. 



254 



DEVELOPMENTAL PATHOLOGY 



Fig. 191 illustrates endarteritis obliterans in the artery of a dog with 
interstitial gingivitis. 

Fig. 192 is from the alveolar process of a tuberculous monkey. 

Fig. 193 illustrates the closing of three arteries from mercurial poison- 
ing. 

Fig. 194 shows endarteritis obliterans with arterial-coat hypertrophy 
in interstitial gingivitis from lead poisoning. 

Fig. 195 shows hypertrophy and endarteritis obliterans in interstitial 
gingivitis from diabetes mellitus. 




Figure 193 
Endarteritis obliterans in mercurial poisoning (original). Three arteries may be seen nearly 
obliterated. The trabeculae with round cell infiltration is easily distinguished. 



Fig. 196 illustrates hypertrophy of three arteries in a syphilitic. 

No structure affords such a favorable opportunity for the study of 
endarteritis obliterans as the alveolar process in animals and human, 
since it can be obtained in quantities at all times and under all conditions. 
It may be produced in healthy animals by the internal administration of 
drugs, metals and other poisons. 



A STUDY IN DEGENERATIVE EVOLUTION 



255 




Figure 194 
Endarteritis obliterans in diabetes mellitus (original). In the upper right hand corner, the 
root of the tooth is seen. The fibrous tissue of the peridental membrane and the 
trabeculae are continuous with round cell infiltration. 




Figure 195 
Endarteritis obliterans in diabetes mellitus (original) 



The bone has entirely absorbed, 



256 DEVELOPMENTAL PATHOLOGY 

Calcic Deposits 

From what has been said and demonstrated by the illustrations, it 
would seem that in those cases where interstitial gingivitis and endarteri- 
tis obliterans have occurred, the old theory that serumal deposits are 
deposited from the blood vessels would be faulty teaching. Since there is 
no circulation in the blood, deposits could not take place from this source. 

Again, if the theory were tenable, such large deposits as found on the 
roots of some teeth could not arise from the blood stream. 

After years of study upon animals and human in regard to those 
deposits, I concluded these deposits did not come direct from the blood, 




Figure 196 
Endarteritis obliterans in a syphilitic (original). 

as advocated by Dr. Ingersoll, but represent the residue of the absorbed 
alveolar process about the root (Fig. 19?) of the tooth. This material, 
floating in fluids (saliva, pus, etc.,), is attracted to the root of the tooth in 
a similar way to the formation of stalactites or stalagmites in a cave. 
Sometimes only a small amount is deposited at some particular locality 
on the root, showing that poisons are circulating in only a few arteries and 
interstitial gingivitis has taken place in a small area. Absorption of the 
alveolar process, however, has occurred, and the debris has collected at 
that particular spot. Again, the entire side of the root may be involved 
or only the apical end of the root. The deposit is always circumscribed 
in the area of inflammation. The method of testing the calcium salts in 
the fluids about the absorbed alveolar process and roots of the teeth is very 
simple. 

Take the contents of a pocket and dissolve it in hydrochloric acid, 
add three times its bulk of water, to this add ammonia, which will precipi- 
tate the phosphate and the calcium. The same results may be obtained 



A STUDY IN DEGENERATIVE EVOLUTION 257 

by rinsing a freshly extracted tooth of a pyorrhoea case in cold water. 
With a stiff brush remove the accumulation and place it in a test tube, 
add hydrochloric acid and more water if necessary. To this add a solution 
of ammonia and the lime salts are precipitated. 




Figure 197 
Calcic deposits from absorbed alveolar process upon the palatine root ol a molar tooth 

(original). 

Roots of teeth that have jbecome entirely denuded of peridental 
membrane and bathed in pus accumulate large quantities of calcic deposits 
direct from the destroyed alveolar process. 

Summary 

The tortuous end-arteries of the alveolar processes are peculiarly 
susceptible to endarteritis, a chronic productive inflammation of the 
internal coat. The causes may operate from within or from without. 

Internal causes include trophic changes and toxins. External causes 
comprise all forms of local irritation, operating through the external to 
the internal coat. Predisposing influences are constitutional diseases, 
drugs, heredity and nervous instability. 



258 DEVELOPMENTAL PATHOLOGY 

Calcic deposits in endarteritis and gingivitis represent the debris of 
the partly absorbed alveolar processes about the roots. Their character 
as calcium salts can be determined by dissolving in hj^drochloric acid and 
precipitating the calcium and phosphates with ammonia. 



Chapter XXII 
PUS INFECTION 

IN the chapter on "Interstitial Gingivitis," it was shown how inflamma- 
tion of the alveolar process might be caused by infection, by mechani- 
cal or local irritation and by substances within the organism without 
the aid of infection, namely irritants in the blood stream. In the last 
named group, the irritations may be due to drug or metal poison, poisonous 
gases or the result of metabolic disturbance whereby the products of 
metabolism are deposited in the arteries and capillaries in the alveolar 
process. Each irritant may set up interstitial gingivitis in a different part 
of the alveolar process, and thus be confined to that particular locality. 
On the other hand, the inflammation may spread to the neighboring tissue 
and the entire alveolar process may become involved. 

When the inflammatory exudate is made up of leucocytes, there is 
produced within the tissue small round-cell infiltration which becomes so 
thick as to obscure the tissue. When the leucocytes are in large numbers 
upon the surface of the mucous membrane about the cervical margin of 
the alveolar process, their appearance on the inflamed surface is that of 
a white fluid which is called pus. This leads to a superficial loss of sub- 
stance and is known as ulceration or purulent catarrh. When the leuco- 
cytes collect in arge numbers, within the tissue, and are followed by lique- 
faction and dissolution of the tissue, it is called an abscess. The alveolar 
process may -be destroyed by interstitial gingivitis; it is only necessary 
there should be a low form of inflammation taking place in and about 
the arteries and capillaries to produce absorption of bone. This is what 
occurs in fully ninety per cent of patients. In the other ten per cent, 
the infection or irritation is more severe and the inflammatory exudate is 
made up of leucocytes in which the small round-cell inflammation is violent 
causing either pyorrhoea alveolaris, dento-alveolar abscess or peridental 
abscess, according to the nature of the infection and its location. Having 
outlined the process of pus infection and formation, let us follow the course 
of the different inflammations as they actually occur in practice. First 
of all, however, note that the inflammatory process, interstitial gingivitis, 
always precedes pus infection. The universal custom of calling a disease 
of the alveolar process pyorrhoea alveolaris is untenable and misleading. 

Pyorrhoea Alveolaris begins with a local irritation from any 
cause which sets up inflammation (interstitial gingivitis) at the gingival 
border of the gum tissue (Fig. 198). The inflammation spreads through 

259 



260 



DEVELOPMENTAL PATHOLOGY 




Figure 198 
Inflammation of the gum margin (original). 




Figure 199 

Section deeper at the alveolar border (original). Active inflammation around two arteries 

which are becoming thickened. 



A STUDY IN DEGENERATIVE EVOLUTION 



261 




Figure 200 
Active inflammation in peridental membrane and trabeculae (original). 







Figure 201 
Violent inflammation in the peridental membrane and trabeculae (original) . 



262 



DEVELOPMENTAL PATHOLOGY 



the arteries (Fig. 199) into the deeper tissue of the peridental membrane 
and alveolar process (Fig. 200). Round cell infiltration rapidly increases, 
but some of the fibrous tissue may yet be seen. The bone has been de- 
stroyed, beginning at the gum margin or in the peridental membrane and 
extending toward the apical end of the root or outward toward the mucous 
membrane of the mouth. Nothing remains but the trabeculae or fibrous 
tissue which originally held the bone cells. The irritation is now so great 
that the exudate of round cell inflammation rapidly increases, until the 
tissues are entirely obliterated (Fig. 201). The leucocytes now collect in 
large numbers within the fibrous tissue. Liquefaction and disintegration 
of tissue occurs, forming pus pockets (Fig. 202). 




Figure 202 
Shows the root of the tooth, the peridental membrane, active inflammation in the trabeculae 
and the formation of two abscesses. Note that both these abscesses are located in what 
was once the avleolar process. The peridental membrane can be readily observed 
between the root of the tooth and the nearest abscess (original) . 

Dento-Alveolar Abscess is a term applied to an accumulation of 
pus at the apical end of the root of a tooth due to death of the dental pulp 
and other irritations. When death of the pulp occurs, decomposition 
takes place and gases form in the pulp chamber. The gases expand and 
an outlet is acquired through the end of the root of the tooth. These gases 
and other irritations set up inflammation in the peridental membrane. 



A STUDY IN DEGENERATIVE EVOLUTION 



263 



The other irritations may be foreign substances forced through the end 
of the root or poisons in the organism passing through the blood stream. 
These irritants set up interstitial gingivitis in the arteries running through 
the peridental membrane and also into the alveolar process and maxillary 
bone. Interstitial gingivitis becomes quite diffused. Bone absorption 
(halisteresis and Volkmann's canal absorption) immediately takes 4 place 
and a considerable area of bone about the end of the root is destroyed, 





Figure 203 
Thickening of the peridental membrane and trabeculae (original). 




Figure 204 
Shows the removal of the outer plate of bone and exposing the root of the tooth and the 

alveolar abscess (original). 



264 



DEVELOPMENTAL PATHOLOGY 



leaving the fibrous tissue (formerly the trabeculae of the bone) in a thick- 
ened condition tightly attached to the end of the root (Fig. 203). 

As absorption proceeds, the lime salts in the inflamed area are thus 
destroyed and the fibrous tissue or trabeculae become organized (Fig. 
204). If the tooth is extracted before liquefaction occurs, the fibrous mass 
may be removed insitu (Fig. 205). A low microscopic section of this 




Figure 205 
Tooth with abscess attached removed from the bone (original). 



J> 




Figure 206 
Microscopic illustration of the end of the root of the tooth, (A) dentine; 
(C) thickening of peridental membrane and abscess; at (Z>) ar< 
liquefaction (original) . 



(B) cementum; 
two points of 



A STUDY IN DEGENERATIVE EVOLUTION 



picture shows the end of the root with fibrous mass attached and degenera- 
tion and liquefaction of tissue just commencing at two points near the 
center of the mass (Fig. 206 d). A higher magnification showing round- 
cell infiltration and breaking down of tissue, liquefying into pus is seen in 
Fig. 207. The pyogenic membrane forming the abscess walls is well 
shown. 




Figure 207 
Microscopic alveolar abscess sac (original) . 

The cause of the irritation producing interstitial gingivitis may be so 
severe and active that not only is there destruction of bone but also of the 
trabeculae. Under such conditions the root of the tooth is seen denuded 
of surrounding tissue (Fig. 208) . 




Figure 208 
Tooth showing formation and destruction of abscess with carious cavity (original). The 
irritation which caused the inflammation and formed the abscess was so great as to 
cause destruction of the sac. 



%m DEVELOPMENTAL PATHOLOGY 

Caries or Necrosis is liable to occur under such violent conditions. 
When caries results, what is generally understood as a cold or blind abscess 
occurs. 

Peridental Abscesses were first described by Dr. Edwin T. Darby, 
of Philadelphia, in 1880. These abscesses are always located in the alveo- 
lar process between the gingival border and the apical end of the root of 
the tooth. Abscesses in this locality are always the result of irritants of a 
toxic nature in the blood stream. Irritants and toxins may be drug or 
metal poisons or autointoxication due to intestinal putrefaction and to 
faulty metabolism. These poisons, circulating in the blood, collect in the 
arteries and capillaries in the alveolar process and frequently produce 
different colors in the mucous membrane; thus, the blue line of lead, the 
red of mercury, the green of brass. Not infrequently blue spots, some- 
times round and sometimes long, are seen at different localities under the 
mucous membrane over the alveolar process. They appear to be an 
accumulation of indican in the tissue under the mucous membrane. Those 
persons who are seriously affected by intestinal fermentation and putre- 
factive changes due to meat-eating have an accumulation of indican in 
the blood vessels for weeks and months before serious results occur in the 
alveolar process or other parts of the body. Again, a very small amount 
of indican or other poisons, accumulations of only a few weeks, will cause 
considerable disturbance in the alveolar process as well as in other body 
organs. 




Figure 209 
Active inflammation of peridental membrane due to mercurial poisoning (original) . 



A STUDY IN DEGENERATIVE EVOLUTION 267 

The history of the formation of a peridental abscess is like that already 
described in relation to the dento-alveolar abscess due to gases. The 
nerves and arteries enter the alveolar process and pass through as far as 
the root of the tooth. The poisons set up irritation in the arteries and 
vessels of Von Ebner and halisteresis and Volkmann's canal absorption 
results. Abscesses form in the area of the trabeculae and discharge their 
contents upon the surface of the alveolar process. 

Cases in Point. A few illustrations of peridental abscess will not be 
out of place. Fig. 209 illustrates active inflammation of the peridental 




Figure 210 
Breaking down of tissue and the formation of abscesses due to mercurial poisoning (original) . 

membrane in a dyspeptic, debilitated, asthmatic forty-eight-year-old 
merchant, who had been under calomel and tonic treatment for less than 
two weeks. When he came under observation, the mucous membrane 
and gums were much inflamed, marked sialorrhea, teeth loose, the gums 
swollen, with pus oozing from them and the breath had a decided metallic 
odor. At my suggestion his physician stopped the calomel. In a few 
days, the soreness and swelling were so reduced the deposits could be 
removed. When the patient was discharged cured, the entire buccal 



DEVELOPMENTAL PATHOLOGY 




Figure 211 
Active inflammation of peridental membrane and trabeculae due to lead poisoning (original) . 




Figure 212 
Four abscesses due to lead poisoning (original). The root of the tooth may be seen in the 
right hand corner, a little higher up an abscess is forming in the peridental membrane. 
Three abscesses are forming in the trabeculae which was originally alveolar process. 



A STUDY IN DEGENERATIVE EVOLUTION 269 

cavity was in a healthy condition, other than the right inferior second 
molar, which required removal. This tooth was placed immediately in 
fifty per cent alcohol for twenty-four hours, then absolute alcohol for 
twenty-four hours more. The membranes had receded about two-thirds 
the length of the root. Sections for microscopic purposes were made from 
the lower third of the root. Of these sections a small fragment of inflamed 
peridental membrane and trabeculae is observed. Fig. 210 exhibits 
violent round cell inflammations, degeneration and liquefaction of tissue 
or abscesses. 

A thirty-five-year-old diabetic painter came under observation for 
lead poisoning. His gums were swollen, there was decided sialorrhea, the 
teeth were loose, and pus flowed from the gums. Three loose teeth were 
removed and placed in alcohol. Sections from the upper third of the left 
superior second bicuspid, on microscopic examination, gave results similar 
to those already described in mercurial poisoning. Fig. 211 shows round 
cells of inflammation. Fig. 212 illustrates very marked degeneration of 




Figure 213 
Four abscesses in the peridental membrane and trabeculae in a diabetic man (original). 

the peridental membrane and trabeculae. In the right hand corner are 
seen the root of the tooth dentin and cementum. The whole surface of 
the membrane is in an advanced stage of inflammation. Just at the 



270 



DEVELOPMENTAL PATHOLOGY 



border of the root is evident an area of membrane softening. Just beyond, 
but joining, is noticeable breaking down of tissue. In the center are seen 
two areas of softened tissue more advanced in degeneration. 

Two cases from my collection of slides excellently show peridental 
abscess. These illustrate the wide range of diseases in which it may occur. 
Fig. 213 illustrates the four stages of abscess in the peridental membrane 
and trabeculae of a sixty-eight-year-old man, a contractor. He was a 
diabetic, and a neurasthenic with autointoxication, which finally culminated 
in kidney lesions. The illustration shows active inflammation at different 
points, the two lower areas breaking down and liquefaction of tissue. The 
upper space shows an abscess with bacteria within, while without is seen 
round-cell inflammation. 

The following scorbutic case was referred to me by Dr. George W. 
Johnson of Chicago: A twenty -five-year-old American was admitted to 
Cook County Hospital for the Insane, December 2, 1892, suffering with 
melancholia, attended by delusions of persecution, and suicidal tendencies 
marked by refusal of food. Through the kindness of Dr. Johnson, I was 
allowed to see this patient. I found none of the teeth very loose, showing 




Figure 214 
Active inflammation in the trabeculae of a scurvy patient (original). 



A STUDY IN DEGENERATIVE EVOLUTION 



271 



the disease was superficial. I removed two teeth that were decayed and 
the most loose. These were prepared for the microscope in the usual way. 
Fig. 214 shows the gums and peridental membrane and trabeculae in an 
active state of inflammation. Small blood vessels are observed in different 
localities, with round-cell infiltration extending into the tissue. Fig. 215, 




Figure 215 
Active inflammation around an artery with liquefaction and formation of an abscess in same 

patient (original). 

the root of the right superior second bicuspid with peridental membrane 
and trabeculae attached, shows active inflammation about an artery 
which has thickened, and an area of tissue degeneration forming an abscess. 

Summary 



When, in the course of interstitial gingivitis, the exudates consist of 
leucocytes, round-cell infiltration takes place, producing pus, leading to 
ulceration and abscess. 

These conditions take the form of pyorrhoea alveolaris, dento-alveolar 
abscess, or peridental abscess. 



272 DEVELOPMENTAL PATHOLOGY 

Pyorrhoea alveolaris results from local irritation at the gingival 
border of the gum tissue, spreading through the arteries into the alveolar 
processes, absorbing the latter and exudating leucocytes. 

Dento-alveolar abscess is essentially a similar process at the apical 
root of the tooth, due to irritation set up by the gases and poisons of a dead 
pulp. When caries ensues, a cold or blind abscess results. 

Peridental abscesses are located between the gingival border of the 
gum and the apical root, and are always due to toxins in the blood, often 
to autotoxemia. The poisons frequently collect in the vessels of the 
alveolar process, showing as colors in the mucosa, e. g. the blue line of lead, 
red line of mercury, green of brass, and blue spots of indican. The path- 
ology is essentially the same as the two former conditions. 



Chapter XXIII 
THE VAULT 

AFTER considering the jaws, their alveolar processes and the dental 
arches, it is now the intention to study the vault. The shape and 
position of the vault depends upon the shape and position of these 
structures. 

Three normal types of vault are recognized, the large, round, low 
vault, with a normal dental arch of the brachycephalic and the large, long, 
higher vault, with normal dental arches of the dolichocephalic. These 
two extremes blend and the mesaticephalic vault results, which may be 
normal or abnormal in outline, according to the size of the jaw in its relation 
to the number of the teeth. 

The shape of the vault takes the general contour of the three types 
of head. Where measurements are taken, there is the greatest variance 
in all directions, showing that no two are alike in nationality or class. 

Measurements were made of vaults among Caucasians and negroes 
who possessed large, well developed, normal jaws, dental arches and vaults. 
There were twelve brachycephalic, twelve mesaticephalic, six dolichocepha- 
lic, Caucasian; there were six each brachycephalic, mesaticephalic and 
dolichocephalic, negroes. While a larger number would perhaps give 
better results, yet there are a sufficient number to show the variability of 
the class. 

The height of the vault was obtained by a specially made instrument 
called a palatometer. The extreme points of the instrument (Fig. 216) 
rest on the superior alveolar process between the second bicuspid and the 
first permanent molars. With the left hand, the shaft at the handle is 
turned, carrying the perpendicular shaft, upon which the scale is engraved, 
up to the center of the vault. When the instrument is removed, the 
height of the vault is readily noted upon the scale. 

Upon examination of the figures of the brachycephalic, white, the 
first six lateral cephalic indexes are 84. Taking the width of the dental 
arch we find that it varies from 2.12 to 2.62; outside second bicuspids, 
from 1 . 75 to 2 . 37; width of vault between second bicuspids, from 1 to 1 . 37; 
antero-posterior, from 1.87 to 2.37, while the height of the vault varies 
from .44 to .62. In the mesocephalic, white, the range varies from 2 to 
2.50 in width of dental arch; width outside of second bicuspids, from 1.62 
to 2.25; width inside second bicuspids, from 1 to 1.86; antero-posterior, 
from 2 to 2.37, and height of vault, from .31 to .68. Dolichocephalic: 
The range width of dental arch is from 2 to 2.37; width outside second 

273 



274 



DEVELOPMENTAL PATHOLOGY 




Figure 216 
Palatometer (original). This instrument is for the purpose of measuring the height of the 
vault. The instrument held in the right hand is placed upon the gum margin between 
the second bicuspids and first permanent molars. The box on the end of the central 
arm is on a level with the points of the instrument. With the left hand, the shaft is 
turned which carries the measure arm to the vault of the mouth. The instrument is 
then removed and the height of the vault is registered upon the instrument. 



A STUDY IN DEGENERATIVE EVOLUTION 



275 



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53.84 
53.84 
55.37 
58.67 


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WIDTH BETWEEN 
2ND BICUS- 
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278 



DEVELOPMENTAL PATHOLOGY 
BRACHYCEPHALIC— COLORED 



NO. 


H 
Q 
g 


WIDTH OUT- 
SIDE 1st 
MOLAR. 


WIDTH OUT- 
SIDE 2nd 
BICUSPIDS. 


1 

WIDTH HE- 1 

ANTERO-POS- HEIGHT OF 
TWEEN 2ND „™rr,™,, 

TERIOR. VAULT. 
BICUSPIDS. 




In. 


Mm. 


In. 


Mm. 


In. 


Mm. I In. 


Mm. In. 


Mm. 


1 

2 
3 
4 
5 
6 


87 
87 
85 
84 
84 
81 


2.87 
2.50 
2.37 
2.25 
2.50 
2.50 


72.90 
63.50 
60.20 
57.15 
63.50 
63.50 


2.00 
2.25 
2.00 
2.00 
2.12 
2.00 


50.80 
57.15 
50.80 
50.80 
53.84 
50.80 


1.31 
1.62 
1.37 
1.31 
2.50 
1.37 


33.27 
41.15 
34.77 
33.27 
63.50 
34.79 


2.18 
2.12 

2.00 
2.25 

2.25 


55.37 j 0.56 
53.84 0.50 
0.62 
50.80 0.75 
57.15 0.50 
57.15 j 0.75 


14.22 
12.70 
15.74 
19.05 
12.70 
19.05 



MESOCEPHALIC— COLORED 







WIDTH OUT- 


WIDTH OUT- 


WIDTH 


ANTERO- 


HEIGHT OF 




X 


SIDE 1st 


SIDE 2nd 


BETWEEN 2ND 


POSTERIOR. 


VAULT. 


NO. 


g 


MOLAR. 


BICUSPIDS. 


BICUSPIDS. 








In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


1 


80 


2.50 


63.50 


2.25 


57.15 


1.62 


41.15 


2.31 


58.67 


0.62 


15.74 


2 


79 


2.81 


71.37 


2.50 


63.50 


1.62 


41.15 


2.25 


57.15 


0.62 


15.74 


3 


79 


2.25 


57.15 


2.00 


50.80 


1.50 


38.10 


2.00 


50.80 


0.62 


15.74 


4 


78 


2.50 


63.50 


2.50 


63.50 


1.50 


38.10 


2.37 


60.20 


0.62 


15.74 


5 


78 


2.12 


53.84 


1.50 


38.10 


1.31 i 33.27 


2.12 


53.84 


0.62 


15.74 


6 


75 


2 . 37 60 . 20 


2.00 


50.80 


1.37 1 34.79 






0.50 


12.70 



DOLICHOCEPHALIC— COLORED 







WIDTH OUT- 


WIDTH OUT- 


WIDTH 


ANTERO- 


HEIGHT OF 




X 


SIDE 1st 


SIDE 2nd 


BETWEEN 2ND 


POSTERIOR. 


VAULT. 


NO. 


Q 
g 


MOLARS. 


BICUSPIDS. 


BICUSPIDS. 








In. Mm. 


In. Mm. 


In. 


Mm. 


In. ' Mm. 


In. 


Mm. 


1 


70 


2.12 ! 53.84 


1.87 47.49 


1.18 29.97 


2.18 55.37 


0.56 


14.22 


2 


69 


2.50 63.50 


2.12 


53.84 


1.50 38.10 


2.25 57.15 


0.62 


15.74 


3 


67 


2.50 


63.50 


2.18 


55.37 


1.50 ; 38.10 


2.25 


57.15 


0.62 


15.74 


4 


67 


2.25 


57.15 


2.00 


50.80 


1.18 29.97 


2.25 


57.15 


0.62 


15.74 


5 


63 


2.25 


57.15 


2.12 1 53.84 


1.50 38.10 


2.25 57.15 


0.62 


15.74 


( 


60 


2.50 63.50 


2.25 | 57.15 


1.75 44.45 


2.37 ' 60.20 


0.68 


17.27 



A STUDY IN DEGENERATIVE EVOLUTION 
BRACHYCEPHALIC, AVERAGE— WHITE AND COLORED 



279 



RACE. 


WIDTH 

outside 1st 

MOLAR. 


WIDTH 

OUTSIDE 2ND 

BICUSPIDS. 


WIDTH 
INSIDE 2ND 
BICUSPIDS. 


ANTERO- 
POSTERIOR. 


HEIGHT OF 
VAULT. 




In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


In. Mm. 


In. 


Mm. 


White .... 
Colored. . . . 


2.22 
2.33 


56.38 
59 . 18 


1.98 
2.06 


50.29 
52.32 


1.19 
1.53 


30.22 
38.86 


2.16 54.86 
2.16 54.86 


0.54 
0.61 


13.71 
15.49 



MESOCEPHALIC, AVERAGE— WHITE AND COLORED 



RACE. 


WIDTH 

OUTSIDE 1ST 

MOLAR. 


WI 

OUTSII 

BICU 


DTH 

)E 2nd 

SPIDS. 


WIDTH 
INSIDE 2ND 
BICUSPIDS. 


ANTERO- 
POSTERIOR. 


HEIGHT OF 
VAULT. 




In. Mm. 


In. 


Im. 


In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


White.. .. 
Colored — 


2.21 56.13 
2.42 1 61.36 


1.95 
2.12 


48.53 
53.84 


1.16 
1.49 


29.47 
37.55 


2.18 
2.16 


55.37 

54.86 


0.52 
0.60 


13.20 
15.24 



DOLICHOCEPHALIC, AVERAGE— WHITE AND COLORED 





WIDTH 


WIDTH 


WIDTH 


ANTERO- 


HEIGHT OF 




OUTSIDE 1ST 


OUTSIDE 2ND 


INSIDE 2ND 


POSTERIOR. 


VAULT. 


RACE. 


MOLAR. 


BICUSPIDS. 


BICUSPIDS. 








In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


In. 


Mm. 


White.. . 


2.19 


55.62 


1.97 


50.03 


1.50 


38 . 10 


2.18 


55.37 


0.74 


18.79 


Colored.. . 


2.35 


59.69 


2.09 


53.08 


1.42 36.06 


2.26 


57.40 


0.62 i 15.74 



bicuspids, 1.87 to 2.12; width between second bicuspids, from 1.25 to 
1.50; antero-posterior, from 2.12 to 2.31; height of vault, from .62 to 
.81. 

The range of figures in each group is so great, and differs so much 
from each other, that it will be impossible to say that any two possess the 
slightest resemblance to each other. By comparing one group with another, 
it will be seen that there is very little difference as regards width and 
length of dental arch, and width of vault. There is, however, quite a 
difference in height of vault. 

By comparing the figures in the table of the lateral index, we do not 
observe the slightest resemblance in width, height or temperament, nor 



280 DEVELOPMENTAL PATHOLOGY 

can we observe the slightest resemblance in the contour of the vault and 
head. It has been claimed that the shape of the vault is influenced by the 
intellect of the individual; that is, the most intellectual people possess 
the highest vaults. With a view of ascertaining the correctness of this 
theory, I measured the heads of six brachycephalic (Plates 29 and 30),* 
six mesocephalic (Plates 31 and 32), and six dolichicephalic (Plates 33 and 
34), colored people — waiters in hotels and restaurants. The white people 
examined consisted of bankers, editors, medical men, students, architects, 
bookkeepers — in fact, the most intelligent men that I could find. 

By comparing the brachycephalic heads we notice that the highest 
lateral index in the white individuals is 84, in colored 87. The highest 
width, outside of first permanent molar, is white 2 . 62, colored 2 . 87. This 
seemed to me quite remarkable. The lowest white 2, colored 2.25. In 
width of vault, between second bicuspids, highest, white 1 . 37, colored 
1.62; lowest, white 1, colored 1.31. Antero-posterior, greatest length, 
white 2.50, colored 2.25. Height of vault, highest white 68, lowest 37, 
with an average of 54; colored highest 75, lowest 50, with an average 
of 61. 

Mesocephalic — Highest lateral index, white 79, colored 80. Highest 
width outside first permanent molar, white 2.50, colored 2.81; lowest, 
white 2, colored 2. 12. Width of vault between second bicuspids, highest, 
white 1 . 86, colored 1 . 62; lowest, white 1, colored 1.31. Antero-posterior, 
highest, white 2.37, colored 2.37; lowest, white 2, colored 2. Height of 
vault, highest, white .68, colored .62; lowest, white .31, colored .50; 
average, white .52, colored .60. 

Dolichocephalic — Highest lateral index, white 72, colored 70. Great- 
est width outside first molar, white 2.37, colored 2.50; lowest, white 2, 
colored 2.12. Width of vault between second bicuspids, highest, white 
1 . 50, colored 1 . 75; lowest, white 1 . 25, colored 1 . 18. 

Antero-posterior — Greatest length, white 2.31, colored 2.37; smallest 
white 2.12, colored 2.18. Height of vault, highest, white .81, colored 
.68; lowest, white .62, colored .56; average, white .74, colored .62. 

In reviewing the figures we notice that the colored people possess the 
roundest heads, while the width of jaw is larger in white, but in the other 
divisions the jaws are more uniform in width. 

A point which must not be lost sight of, and one that I have frequently 
noticed in ancient skulls, is that in the colored race the jaw does not dimin- 
ish in width anterior to the first permanent molar as it does in the white 
race. The height of vault seem to be much greater in the colored race 
than in the white, with the exception of the dolichocephalic heads, where 
it is higher in the white race. The height of vault, like other measurements, 
is more uniform in the white race. Comparing the figures of the colored 
* See "Osseous Deformities of the Head, Face and Teeth." 



A STUDY IN DEGENERATIVE EVOLUTION 



281 



with white people it will be seen, in the average, that the width and antero- 
posterior measurements of the colored people are the largest. 

Since the highest vaults in the brachycephalic and mesocephalic heads 
are found among colored people, and in the dolichocephalic among the 
white, we must conclude that intelligence has nothing whatever to do 
with the contour of the vault, and that there is no more comparison between 
the vault and the contour of the heads of colored people than there is in 
white individuals. 

The most striking point, in a general way, is the fact that the jaws of 
the negroes are the largest and their vaults are the highest. This is to 
be expected, since in phylogeny, the negro is the highest in normal phy- 
sical development. Changes in size and shape of the vault take place 
rapidly in evolution and degeneration of the Caucasic races from the high- 
est physical type. 

Deformed Vaults are due (l) to an irregularity in the arrangement 
of the dental arch, (2) to an abnormal development of the median suture 
and (3) to the hypertrophy of the alveolar process and maxillary bones. 
Irregularities in arrangement of the dental arch are the result of two 
causes : (l) neuroses of development, producing arrest of development of 
the maxillary bone; (2) local causes, or accident. Those produced by an 
arrest of development take typical forms, which I have classified and de- 
scribed in another chapter by taking 3,000 models of irregularities of the 
teeth and grouping them under the heads of V, partial V, semi V, saddle, 
partial saddle, and semi-saddle. The irregularities of the teeth produced 
by local causes do not take typical forms but are as numerous as the cases. 

The different forms of dental arches due to neuroses of development 
are discussed and illustrated in Chapter XVIII, "The Dental Arches." 

The following tables will exhibit the differences in the heights of vaults, 
both in normal and defective jaws. The height is taken centrally and 
vertically from the gingival plane on a transverse line intersecting the 
gingival crests between the second bicuspids and first molars. 



NORMAL JAW 



Height 


No. of 


Height 


No. of 


Height 


No. of 


Height 


No. of 


of Vault. 


Cases. 


of Vault. 


Cases. 


of Vault. 


Cases. 


of Vault. 


Cases. 


.21 


1 


.40 


159 


.56 


936 


.71 


149 


.25 


2 


.43 


182 


.59 


218 


.75 


427 


.28 


70 


.46 


69 


.62 


514 


.78 


69 


.31 


171 


.50 


199 


.65 


150 


.81 


75 


.34 


169 


.53 


429 


.68 


568 


.84 


12 


.37 


146 















Total number of cases, 4,614. Average height of vault, .58 of an inch. 



282 



DEVELOPMENTAL PATHOLOGY 
SADDLE-SHAPED ARCH 



Height 


No. of 


Height of 


No. of 


Height of 


! No. of 


Height of 


No. of 


of Vault. 


Cases. 


Vault. 


Cases. 


Vault. 


Cases. 


Vault. 


Cases. 


.21 




.40 




.56 


6 


.71 


5 


.25 




.43 




.59 


5 


.75 


5 


.28 




.46 


3 


.62 


4 


.78 


1 


.31 




.50 


5 


.65 




.81 


1 


.34 




.53 


5 


.68 


3 


.84 




.37 


1 










.. 





Total number of cases, 44. Average height of vault, .60 of an inch. 



V-SHAPED ARCH 



Height 


No. of 


Height 


No. of 


Height 


No. of 


Height 


No. of 


of Vault. 


Cases. 


of Vault. 


Cases. 


of Vault. 


Cases. 


of Vault. 


Cases. 


.21 




.40 


1 


.56 


15 


.71 


1 


.25 




.43 




.59 


4 


.75 


2 


.28 




.46 


3 


.62 


9 


.78 




.31 


2 


.50 


8 


.65 




.81 


1 


.34 




.53 . 


3 


.68 


5 


.84 




.37 


4 















Total number of cases, 58. Average height of vault .55 of an inch. 



SEMI-V AND SEMI-SADDLE-SHAPED ARCH 



Height 


No. of 


Height 


No. of 


Height 


No. of 


Height 


No. of 


of Vault. 


Cases. 


of Vault. 


Cases. 


of Vault. 


Cases. 


of Vault. 


Cases. 


.21 




.40 




.59 


i 


.« 




.25 


1 


.43 


1 


.62 


4 


.78 


1 


.28 




.46 




.65 


2 


.81 




.31 




.50 


3 


.68 




.84 




.34 




.53 


3 


.71 


2 






.37 


1 


.56 


5 











Total number of cases, 24. Average height of vault, .56 of an inch. 



By comparing the measurements of normal with deformed vaults, 
it will be seen that there is as wide a range in height among normal vaults 
as in the deformed. In the normal vaults . the greater number is found at 
.71 of an inch in height, while in the deformed vaults the greater range is 



A STUDY IN DEGENERATIVE EVOLUTION 283 




Figure 217 
Casts of jaws of children from two to six years of age (original). The vaults are low, almost 
flat, and ossification of the suture has occurred. 



284 DEVELOPMENTAL PATHOLOGY 

from .71 to .78 of an inch. The average height of deformed vaults is 
practically the same as that of healthy normal vaults. The difference is 
due to the narrow contracted dental arch and is apparent and not real. 

There is quite a range in height in normal as well as in deformed 
vaults. The range, however, varies but little in each class. Since, there- 
fore, there are high vaults as well as low in normal dental arches, the theory 
that the vault is carried upwards, by lateral pressure from without, is not 
tenable. There are many other reasons to show why this theory is fallaci- 
ous. These are discussed elsewhere. The one already noted above, 
according to my researches, is sufficient for our purpose in this work. 

What argument can be used to account for high vaults in both normal 
and deformed? A study of Fig. 217 will throw some light upon this 
question. These illustrations are those of children ranging from two to 
six years of age. All have their temporary teeth. No. 6 has the first 
permanent molars coming into place. There is very little difference in 
the height of these vaults. It is after the sixth year that the great change 
in the vault takes place. There is a slight difference in the height of vaults 
in the six illustrations of jaws with deciduous teeth and this difference 
must be accounted for, as well as the greater changes which come later. 

These changes are due to difference in development of the rami in 
which the ontogeny recapitulates the phylogeny consequent upon an 
unstable nervous system. The line of least resistance in rami development 
is not unlike that of jaw development in which the growth takes the line 
of least resistance. 

The line of least resistance is toward the larger rami of the negro as 
well as toward a smaller jaw of evolution. In the person with an unstable 
nervous system, the rami is as liable to develop long as short. 

With this explanation, it will be noted that the rami lengthen out of 
proportion to the jaw development. In order that the teeth may articu- 
late, the alveolar process, (instead of the teeth) grows upwards and down- 
wards to meet the inharmony of development. A slight difference in 
height of vault, therefore, is due to a lengthening of the alveolar process 
downward and not to the vault being carried higher up. The great change 
takes place between the sixth and twelfth year when the second set of 
teeth come into place. The gradual lengthening of the vault is beauti- 
fully demonstrated. 

Any one may verify these statements by taking measurements with 
the author's palatometer (Fig. 216) once a year in a child from two to 
twelve years of age. 

Abnormal Development of the Median Suture. The effect of an 
unstable nervous system on development of the median suture is striking. 
As in all bone development, the cells sometimes develop early and some- 



A STUDY IN DEGENERATIVE EVOLUTION 285 

times they develop in a dense form; sometimes in large quantities, causing 
hypertrophy, and sometimes scantily with little or no union, depending 
upon the nerve control of the vasomotor system and the amount of nutri- 
ment deposited. The median suture, like all other bone structures, may 
have large deposits and ossify early, or they may be scanty and ossification 
take place late in life. Complete ossification occurs as early as two years 
when all the temporary teeth are in position (Fig. 217). In these six 
illustrations, from two to six years, ossification is complete and hypertrophy 
of suture is developing. Sometimes ossification is deferred as late as the 
thirty-sixth year, or even later. An interesting factor in the development 
of the median suture is that of mastication. Similar influences do not enter 
into the uniting of any other suture of the body. The child begins to 
masticate food at about eighteen months, the act of mastication involving 
a lateral movement of the two halves of the superior maxilla. This move- 
ment causes friction, stimulation and irritation. Deposition of bone 
cells, therefore, is attracted, and as ossification proceeds, large masses 
of bone or hypertrophy take place along the suture. The amount varies 
in different localities. The shape also varies. 

Fig. 218 shows the different shapes and positions of the hypertrophy; 
sometimes the hypertrophy is confined entirely to the anterior part of the 
vault; sometimes entirely to the middle portion; and sometimes to the 
posterior part. Ossification of the median suture is frequently slow. 

The following history is to the point. A lady, thirty-six years of age, 
who has been under the author's care for the past fifteen years, has a space 
between the central incisors of .50 of an inch. No space was observed 
until the age of twenty. The teeth filled the arch and all antagonized. 
The lower jaw continued to develop and the act of mastication carried the 
superior maxillary bones laterally, thus widening the suture, the space 
filling in and producing a ridge. The depth of the ridge depends upon 
the amount of irritation. The height of the groove on either side depends 
upon the depth of the ridge. When there are grooves upon either side, 
the jaw is always contracted, the alveolar process being nearer the center 
of the vault. This, together with the ridges, produces the groove. Were 
it not for excessive development of the median suture and a contracted 
dental arch, the vault would take the shape of the dotted lines and be of 
normal development. 

Fig. 219 represents the jaws and teeth of a fifty-year-old man. He 
has been a patient for nineteen years. The space between the central 
incisors has been growing as the lateral expansion of the two halves of the 
maxillary bone has progressed. The continued development of the inferior 
maxilla, the irritation of mastication, and the lateral expansion due to 
lateral pressure of the inferior teeth against the superior, have caused the 



DEVELOPMENTAL PATHOLOGY 



widening of the suture, including the jaws and teeth. The osseous forma- 
tion of the suture causes the frenum of the lip to be elongated. 

When the jaws have developed larger than the long diameter of the 
teeth and there are spaces between the anterior teeth, occasionally local condi- 
tions will cause absorption of bone on the one hand and deposition of bone 
cells on the other, separating the teeth at the median line. 




Figure 218 
Cross section of jaws at the first permanent molar (original). 

the vault and suture. 



Shows the different shapes of 



A STUDY IN DEGENERATIVE EVOLUTION 



287 



Arrests of the bones of the face, nose and superior maxilla in neurotics 
and degenerates frequently occur. Adenoids, hypertrophy and spurs also 
assist in preventing nose breathing. In such cases, it is always advisable 




Figure 219 
Cast of jaw and teeth of a fifty-year-old man (original) . Shows a lateral growth of the maxil- 
lary bone at the median line carrying the teeth laterally. The frenum which has 
developed excessively extends down between the teeth. 

to rapidly separate the superior maxillary bones at the suture by the use 
of jackscrews. Figs. 220 and 221 show the method of the operation. The 
younger the child, the quicker and more satisfactory can this be accom- 
plished, since the procedure is a bending of the bones at the lower or middle 
meatus of the nose. By this method the nasal cavities are enlarged. 




Figure 220 
The application of an appliance for the purpose of opening the suture by spreading the dental 

arch (George V. I. Brown). 



After special treatment by the rhinologist, nose breathing will become 
established and the child will soon improve in health and mentality. The 
opening of the suture may be enlarged to any extent necessary to accom- 



288 



DEVELOPMENTAL PATHOLOGY 



plish the desired result. The lower dental arch must also be expanded to 
form a normal articulation. 

From 1880 to 1894, I had opened the suture at the median line in 
fourteen patients, ranging from twelve to sixteen years of age, with most 
satisfactory results both as to general appearance and to health. 





i h : is 


WW 


H : J 




Ki&fxl 


mm T % \ l 


Fw?Pfj-- 



Figure 221 

Shows the result of spreading the dental arch. The space between the teeth and the opening 

between the maxillary bones is quite marked (George V. I. Brown). 




Figure 222 
Excessive hypertrophy of the alveolar process producing a deformed vault, natural size 

(original) . 



A STUDY IN DEGENERATIVE EVOLUTION 289 




Figure 223 
Excessive development of the alveolar process, producing a deformity of the vault, natural 

size (original). 



Hypertrophy of the Alveolar Process and Maxillary Bones 
producing deformed vaults, was partly considered in Chapter XIX. The 
milder forms were discussed in relation to the shape of the dental arch 
and alveolar process. We shall now consider the subject of actual deformi- 
ty. First, however, it is well to state that what is considered by some 
specialists a deformed vault, arch or palate, is not the seat of the disease, 
the seat of the disease being in the alveolar process and not in the vault. 
The vault is involved only in extreme pathologic conditions, as we shall 
see later. In all three of the jaws illustrated in Chapter XIX, the alveolar 
process alone was involved and not the vault. We can easily understand 
this when we consider that hypertrophy of the alveolar process is rarely, 
if ever, associated with the first set of teeth. The vaults are usually normal. 
Hypertrophy of the alveolar process usually begins after the second set of 
teeth have erupted. 

The alveolar process, being a very transitory loose structure, the 
irritation brought about by the development of teeth and the absorption 
and depositon of bone in persons with an unstable nervous system, causes 
the bone to continue development after the teeth are securely held in 
position, under the law of economy of growth and least resistance. 

Development of the alveolar process may continue so as to involve 
the hard palate and the entire maxillary bone (Fig. 222), carrying the dental 



290 DEVELOPMENTAL PATHOLOGY 

arch laterally to a considerable distance. While in such a state, the vault 
may be considered deformed, although the cause is in the alveolar process 
and not in the hard palate. 

Fig. 223 is another extreme illustration of the same condition. The 
anterior alveolar process is only slightly involved while the part connected 
with the molars is excessively developed. This is also true in the previous 
illustration and, indeed, in most cases. This point is interesting since an 
unstable nervous system, previously acquired, may not manifest itself 
until this very critical time, the fourth period of stress, from fourteen to 
twenty-one years of age. The child may be strong and well until this 
period of stress, when an unstable nervous system may develop. Such 
deformities of the alveolar process are very distressing in many ways. 

First, the teeth are carried out of position so that contact in chewing 
is out of the question. 

Second, the gums frequently hypertrophy and develop below the 
grinding surfaces of the teeth, bleeding easily and thus keeping the mouth 
in a very unhygienic condition. 

Third, the tongue is deprived of free motion to carry the food from 
one side of the mouth to the other; it cannot assist in speech or song because 
it cannot be carried into the roof of the mouth. As a rule, however, such 
a deformity is not externally observable. 

Summary 

The shape and position of the vault depend upon those of the alveolar 
process. 

Three normal types of vault are recognized; the large, round, low, or 
brachy cephalic; the large, long, high or dolichocephalic; and the blend of 
these two, or mesocephalic. 

There is the greatest variation in vaults within normal limits. 

The highest vaults in the brachy and mesocephalic heads are found 
in the colored race; in the dolichocephalic, among the whites. Hence 
intelligence has no relation to the contour of the vault. 

High vaults being normally compatible with normal arches, the theory 
that the vault is carried upward by lateral pressure from without is unten- 
able. Observation shows that the high vault is due to a lengthening 
downward of the alveolar processes to approximate the teeth, in com- 
pensation for inharmony in the length of jaws and rami. 

Abnormal development of the median suture results from premature 
or delayed ossification, due to an unstable nervous system. No other 
suture in the body is subjected to similar conditions of uniting with this 
one, e. g. the friction, stimulus, and irritation of mastication. 



A STUDY IN DEGENERATIVE EVOLUTION 291 

Deformed vaults are caused by (1) irregular dental arches, (2) abnor- 
mal development of the median suture, (3) hypertrophy of the alveolar 
process and the maxillary bone. 

The alveolar process, under an unstable nervous system, may continue 
to develop after the tooth is firmly socketed, and cause hypertrophy, 
deforming the vault. 



Chapter XXIV 
CLEFT PALATE AND HARELIP 

BEAUTIFUL as the human face is, in its most perfect phase, it is, as 
Minot has shown from the standpoint of food-getting, an embryonic 
type. 
An Arrest in Phylogeny. — The jaws are needed less and less for 
purposes of food-getting, chewing, and combat, hence resultant disuse 
under the law of economy of growth sacrifices them for the benefit of 
the growing brain and nervous system and to the need the first has 
of the dermal elements of the skull. Under operation of the law of 
economy of growth there has occurred the esthetic evolution of the face 
from the anthropoid to the Apollo Belvedere type, as well as the reverse 
phase of this, where symmetry of the body as a whole, to preserve brain 
gains is sacrificed to changes in the nose, jaws, alveolar process, vault 
and teeth. This struggle for existence strains most developments of 
points of ossification, and as it is aided by primitive type heredity, spends 
much of its force on the structures which have gained for race purposes like 
the jaws and the teeth. The palatal bones are therefore affected. 

Cleft palate is divisible into congenital and post-congenital. The 
post-congenital, while having a predisposing factor of teratologic ^nature, 
is often produced by a determining nosologic factor. Congenital cleft 
palate is divisible into two kinds, complete and partial — complete, when 
the fissure extends the entire length from the uvula to and including the 
anterior alveolar process and even the lips; partial, when only a small part 
of the structure is involved. Thus the cleft may extend through the 
anterior alveolar process, involving only the incisive bones, which is very 
rare; when present, single or double harelip almost invariably co-exists. 
Cases occur where a small portion of the anterior alveolar process and jaw 
are involved with one or two teeth. The hard palate may be merely 
involved to the extent of a small fissure, or the whole palate may be want- 
ing. The soft palate may contain the cleft, or the uvula alone may. Cases 
occur in which the non-development of the intermaxillary bones produces 
lip fissures. 

The problems involved in cleft palate are those of embryogeny as 
modified by the law of economy of growth by remote atavism, by type 
heredity, and by the results of characters acquired during the periods of 
dentition and adolescence and prior to the senile. As soon as the external 
nares are separated from the mouth in the embryo (Fig. 224) there occurs, 
as Minot has shown, a partition between the nasal pits and the mouth. 
This partition in which the intermaxillary bone is differentiated later, is 

£92 



A STUDY IN DEGENERATIVE EVOLUTION 293 

supplemented by another partition, the true palate, which shuts off the 
upper part of the oral cavity from the lower, thus adding the upper part 
to the nasal chamber. The palate is a secondary structure which divides 
the mouth into an upper respiratory passage and a lower lingual or digestive 
passage. The palate arises as two shelf -like growths of the inner side of 
each maxillary process, and is completed by the union of the two shelves 
in the median line. The shelves so arch as to descend a certain distance 
into .the pharynx, but in the pharynx their growth is arrested, though they 
may be still recognized in the adult. In the region of the tongue, which 



# 



Oral surface of~— * 
maxillary process • 




Dorsum of nose 



Anlage producing 
nasal tip 

^.Lateral nasal pro- 
Nasal groove- - .„, JS WB cess 

-Mesial nasal pro- 
Naso-optic groove^ /* t • -J&^ : JB ; ~~J&T^ ^% cess 

Maxillary process 
of first arch 



Roof of oropharynx 



Figure 224 
Portion of head of about thrity-four days, showing roof of primitive oral cavity (His). 

includes more than the primitive of the oral cavity, the palate shelves 
continue growing. At first they project obliquely downward toward the 
floor of the mouth, and the tongue rises high between them and appears 
in sections which pass through the internal nares to be about to join 
the internasal septum. As the lower jaw grows the floor of the mouth 
is lowered, and the tongue is thereby brought further away from the 
internasal septum. At the same time the palate shelves take a more hor- 
izontal position and pass toward one another above the tongue and below 
the nasal septum, and meet in the median line, where they unite. From 
their original position the shelves necessarily meet in front (toward the lips) 
first, and unite behind (toward the pharynx) later. In the human embryo, 
the union begins at eight weeks, and at nine weeks is completed for 
the region of the future hard palate, and by eleven weeks is usually 
completed for the soft palate also. The palate shelves extend back 
across the third and second brachial arches. By migration of the first 
gill pouch, or in other words of the Eustachian tube, the Eustachian 
opening comes to lie above the palate (uvula), while the second cleft 
remains lower down and lies below the palate as the outline of the tonsil. 



294 



DEVELOPMENTAL PATHOLOGY 



The uvula appears during the latter half of the third month as a pro- 
jection of the border of the soft palate. Soon after the two palatal shelves 
have united, the nasal septum unites with the palate also, and thereby 
the permanent relations of the cavities are established. 

In dealing with the influence of the factors named on embryogeny, 
the influences of disturbances of balance, at an early period, which would 
strengthen disappearing structures at the expense of later acquired struc- 
tures, have to be considered. Such a disturbance would overcome the 
effects of disuse and create over-growths of primitive structures at the 
expense of later acquired structures, leading to arrest, atrophy, or even 
disappearance of these last. The structures of the mouth and nose being 
exceedingly variable in evolution, and the structures of the jaws and teeth 
having in man taken an embryonic trend for the benefit of the body as a 
whole, under the operation of the law of economy of growth, disturbances 
of balance are peculiarly apt to occur here. Not only is actual growth 
upset by the operation of this disturbance of balance, but certain potentiali- 
ties are likewise interfered with. Up to the age of three the central nervous 
system gains at the expense of the other structures. After this period the 
other structures gain, but the nervous system while growing, does not 
maintain its supremacy in growth. 

Interferences with lip and palate formation (Figs. 225 and 226) must 




Figure 225 
A woman with double harelip (Carpenter). 



A STUDY IN DEGENERATIVE EVOLUTION 



295 



begin comparatively early in embryogeny, and hence must imply decided 
defect on the part of the parents. Any maternal factor, whether arising 
during a particular pregnancy or inherited, may so check the development 
of the palate as to produce the various types of deficiency which are observed 
by surgeons. The influence of heredity requires no special discussion, 
since it is involved as a rule in serious general defect rather than in localized. 
Furthermore, maternal environment plays here as elsewhere an enormous 
part. A defective mother may be so influenced by favorable environment 
during the first three months of pregnancy, or by removal from bad parental 
environment during the same period, that the embryo would not only 




Figure 226 
A woman with cleft palate (Carpenter). 



pass through these periods of intra-uterine stress successfully, but would 
likewise acquire increased potentiality of passing through the later periods 
successfully. On the other hand, an evil environment or an environment 
changed for the worse soon after impregnation unfavorably affects embryo- 
geny. 

In dealing with the development of the palate, both pre- and post- 
congenitally, the relations of the hypophysis or pituitary body have to be 
taken into account, since it has been demonstrated that this body exerts 
an influence over body growth and the structures thereto related. The 
hypophysis arises in all vertebrates as an evagination of the ectoderm near 
the dorsal border of the oral plate, but is separated from the plate by a fold 



296 DEVELOPMENTAL PATHOLOGY 

of the ectoderm. The hypophysis at one stage of its development in 
mammals is a diverticulum of the oral cavity with one wall attached to the 
brain and the other formed by a fold dividing the hypophysis from the 
mouth. The hypophysial diverticulum later elongates and its upper end 
expands to a considerable vesicle, the lower end remaining narrow as the 
pedicle. The floor of the brain forms an outgrowth behind the hypophysis 
which is the representative of the infundibulum. The cementing together 
of the buccal and cerebral ectoderm over the hypophysial area causes the 
formation of the two diverticula. The hypophysis then grows rapidly. 
The pedicle elongates and its lumen is obliterated. The mesenchyma 
condenses to form the base of the skull (sphenoid). The pedicle entirely 
aborts, but the position for its passage through the sphenoid, while remain- 
ing for some time after birth in about 10 per cent of children dying in 
hospitals, is ultimately obliterated by growth of the sphenoid cartilage. 
The infundibulum contributes to the production of the adult hypophysis 
in mammals, but in lower vertebrates it persists as an integral part of the 
brain and is differentiated into ganglionic tissue. The pointed end under- 
goes a knob-like enlargement, which later loses its cavity. Although the 
differentiation of nervous tissue begins in it, its cells early acquire an 
indifferent character. It is penetrated by blood-vessels and connective 
tissue, but the connection with the brain is permanently retained. In 
the adult the knob, although regarded as the posterior lobe of the hypophy- 
sis, is in no sense a part of it. Strain on the development of the hypophysis 
after birth can not only produce undue growth of bone, but can also check 
development of it. The influence of the periods of stress during the last 
months of pregnancy may arrest palatal development through interference 
with the bone-forming function of the hypophysis, checking the develop- 
ment of bone and cartilage necessary to proper evolution of the palate. 

"The antecedent," according to Oakley Coles, "which strikes one a 
priori as being likely to play the most important part in the production of 
congenital deformities is that of hereditary influence. But though it will 
be evident that direct influence of heredity in the production of cleft palate 
is marked and undeniable, no sufficient statistics have as yet been brought 
forward to show that the actual presence of deformity in the parent has 
any direct predisposing influence in the child. In other words, though 
the defective conditions which precede and accompany the phenomenon of 
cleft palate are almost certain to be referred to parental influence, it is 
extremely doubtful whether cleft palate is in itself transmissible." Here 
appears that antiquated view of heredity which takes into account only 
direct transmission. Heredity involves the complex of type heredity, 
remote atavism, individual defects or peculiarities of immediate ancestors, 
maternal environment, and stress period environment. Direct heredity 



A STUDY IN DEGENERATIVE EVOLUTION 297 

can occur only when, in embryonic existence, the embryogeny by the law 
of economy of growth is centered around a given line of least resistance 
during the struggle for existence between the organs for assimilable nutri- 
ment. While a defective ancestor may have defective children, the line of 
direct expression of the defect is interrupted by the influence of atavism, 
by the influence of varying environment during embryogeny, and during 
post-natal periods of evolutionary stress. That cleft palate may be 
transmissible, Demarquary, Roux, Trelat, Follin, and Duplay have shown, 
but such transmission is and must be rare, from the factors unfavorable 
to direct transmission entering into heredity, inclusive of maternal environ- 
ment during embryogeny. 

The deformity rarely occurs, if at all, from maternal impressions. 
In most of the cases which have come immediately under notice, when 
one parent had a cleft palate all the children have been born perfectly 
developed, even though dread of transmitting the deformity was never 
absent from the mind of the mother. In one case three members of one 
family have cleft palate — one 17 years, one 30 years, and the third 35. 
The first and last are women; the other is a married man with family with- 
out any trace of the father's deformity. No instance of cleft palate could 
be found among ancestors or collateral branches of the family. In another 
family I have obtained the following remarkable history: G. H. C, born 
1853, perfect; L. C, born 1855, single harelip and cleft palate; J. F. C, 
born 1856, perfect; F. W. C, born 1860, double harelip and cleft palate; 
H. E. C, born 1863, perfect. The paternal grandmother had cleft palate. 
Five per cent of 1,200 criminals examined by Knecht had cleft palate. 
In an examination of 495 criminal boys at the Illinois State Reformatory 
and 1080 at the New York State Reformatory, only one case in each institu- 
tion was observed. Fourteen per cent of the prostitutes examined by 
Pauline Tarnowsky had cleft palates. Langdon Down found only a half 
per cent of cleft palates among congenital idiots. Gresnor found nine 
cases in 14,466 children, or one in 1607. I examined 1977 feeble-minded 
children without finding a single case. In 207 blind but one case was 
observed; in 1935 deaf mutes two cases, or about one in 1,000. The per- 
centage among the defective classes is undoubtedly much larger than 
among normal individuals, but early deaths explain the small percentages. 
Bland Sutton's experiments with dogs indicate not only the presence of 
this deformity among animals, but its transmissal. Hereditary defects 
are evident in the statistics of zoologic gardens. A keeper of the Zoologic 
Gardens in Philadelphia observed cleft palate in the mouths of lion cubs 
born in the gardens. Cleft palates were also observed in a number of pups 
born in Buffalo. Ogle found that 99 per cent of the cubs born in the Lon- 
don Zoologic Gardens had cleft palates. This was ascribed to the artificial 



298 DEVELOPMENTAL PATHOLOGY 

diet of the mother as the result of enforced captivity. Similar results 
in other gardens in Europe were charged to maternal feeding with meat 
without bone. Feeding with the whole carcass of small animals greatly 
diminished these deformities. If cleft palates were sometimes attributable 
to this cause, other bony structures should likewise be involved. It is 
hence not astonishing to find many rickety lions born in captivity. Cleft 
palate has been observed among dogs, sheep, goats, etc. The question 
whether domesticity does not play in them the alleged parasitic influence 
of civilization in man can only be solved by knowledge of deformity fre- 
quency among wild animals of the same zoologic families. 

The difficulties of securing data of the occurence of cleft palate among 
wild animals are sufficiently shown by the following replies to the question : 
" Have you ever observed cleft palate among wild animals not in captivity?" 

Prof. Osborn is in Europe, but in his absence I have attempted to find an answer to 
your query in regard to cleft palate. I looked through Windle's 11th to 15th Report on 
Recent Teratological Literature (Journal of Anatomy and Physiology) and also in several 
encyclopedias and surgical books without success, and I also asked Dr. J. A. Allen, one of 
the leading mammalogists of the country, if he bad ever noted cleft palate in wild animals 
not in captivity, but have not ever noted a case. 

William K. Gregory. 

American Museum of Natural History, New York City. 

In reply to your query I can say that I have never observed and do not recollect having 
heard of case of cleft palate in wild animals not in captivity. 



Queens College, Belfast, Ireland. 

I have not seen a case of cleft palate in any wild animal. 

Edinburgh. 



J. Symmington. 



Wm. Turner. 



I have never observed a case of cleft palate among wild animals, nor have I ever heard 
of one. Several years ago lion whelps were born with cleft palate in the Zoological Gardens 
of London. 

London, England. Bland Sutton. 

I have only experience of wild animals bred in captivity. In the Zoological Gardens of 
Dublin, which I had the supervision of for many years, we have bred lions (between 200 and 
300) since 1856. Only very occasionally did cleft palate or other deformity appear amongst 
the cubs — only once during my time, if I recollect rightly. Of course in my museum work I 
have had many wild animals pass through my hands which were not bred in captivity, and 
I never saw a case of cleft palate. At the same time it should be remembered that many 
collectors would reject a deformed specimen. 

In London Zoological Gardens, cleft palate amongst lion cubs used to be very common, 
I understand. 

University of Edinburgh. D. J. Cunningham. 



A STUDY IN DEGENERATIVE EVOLUTION 299 

In reply to your letter of the 1st inst., I only know of one case of wild animals being 
born with cleft palate. The knowledge of this I owe to Mr. R. T. Powch, superintendent of 
these gardens. He informs me that a litter of tiger cubs born of wild parents were brought 
up by an English lady in Burmah and found to have cleft palate. As you perhaps know, 
lion cubs have so constantly a cleft palate that it seems almost if not quite normal for them 
to be so born in menageries. 

Regent's Park, London, England. Frank E. Beddard. 

This negative evidence is not equivalent to demonstrating absence of 
cleft palate among wild animals, for, as I have elsewhere pointed out, animals 
destroy soon after birth offspring which to them appear peculiar. Cleft 
palate predisposes to infection by pathogenic bacteria, and hence offspring 
born in a wild state are not likely to survive. Cleft palate, moreover, 
is quite frequently associated with deep-seated affections of the nervous 
system or of the locomotive apparatus. 

In the evolution of the palate, ossification is the central point as 
regards completed development. Arrest of ossification or of its potentiality 
plays a considerable part in determining the permanency of cleft palate. 
Reported cases show that the condition is one which sometimes requires 
merely a temporary stimulus to growth to disappear. The arrest is one 
of potentiality, not of permanent development. The palate bone develops 
from a single center at the angle of junction of the two plates of the bone.* 
The center makes its appearance about the second month. Appearing 
thus early, it has an impetus which survives the stress of the different 
periods of intra-uterine development and maternal environment. The 
influence of type heredity aids rather than arrests ossification of the palate, 
since tendency to ossify occurs thus early. 

The relationship between palatal vault deformities and cleft palate, 
pointed out by Oakley Coles, is that existing between atrophies, hypertroph- 
ies, and arrests of development everywhere. Instability of trophic func- 
tions is shown as much in hypertrophies as in atrophies. The instability 
may affect not only development, but potentialities of development, which 
it may arrest ere the period when the potentiality is to pass into fulfilment. 
The same factor which prevents sexual development at the period of 
puberty may prevent proper development of the vault at the sixth year. 
The frequency of what may be called palatal hypertrophy as compared 
with the deficiency shown in cleft palate is an illustration of this impetus. 
The ease with which the tendency to cleft palatal offsprings is remedied 
by diet in the menageries shows that the ossification potentialities need 
but a slight stimulus. Influences interfering with proper development 
of the hypophysis, which is in such close embryogenetic relations with the 
palate, interfere with the onset of ossification, or with its proper develop- 
ment. 

* Gray's "Anatomy." 



300 DEVELOPMENTAL PATHOLOGY 

From the angle of junction of the two plates the bone ossification 
spreads inward to the horizontal plate, downward into the tuberosity, 
and upward into the vertical plate. In the fetus the horizontal plate is 
much longer than the vertical, and even after it is fully ossified the whole 
bone is at first remarkable for its shortness. The palate hence requires 
an additional period to develop after ossification. The complicated rela- 
tions of the palate to the turbinated and maxillary bones, both under 
stress from the law of economy of growth as varying structures, place it 
under varying conditions of nutriment, expressed either in excess or in the 
deficiency shown in cleft palate. The fact that the palate is permanent 
compared with the turbinates and the rest of the maxillary bones indicates 
that, aided by its early ossification tendencies, it tends to survive in the 
struggle for assimilable nutriment. Heredity of long standing sometimes 
so affects early development of the palate, however, as to give the other 
two bones an advantage. This occurs where the preconceptional vitality 
of the mother is lowered, or where the first two months after conception 
are periods of extreme strain for the mother. Paternal vitality when 
lowered affects the early conceptional period. This to some extent involves 
an influence on maternal vitality, since, as has been repeatedly shown, 
chiefly after maternal breakdown does paternal defect show itself. In 
Mongoloid idiocy, as W. A. Hammond has shown, early pregnancies when 
the mother is healthy are free from such offspring, but later births are of 
this type. 

To such extent is this maternal vitality the case that even syphilis 
may not arrest development. Thus, as in a case reported by Engel, the 
husband may be infected during the second month of his wife's pregnancy 
and immediately infect her. A hearty boy is born with copper-colored 
eruption about ihe m anus, and later coryza. These symptoms disappear 
under specific treatment, not to return. The child does not have tertiary 
lues, but unlike the ordinary cases of congenital syphilis, the secondary 
stages. 

The factors involved in the reproduction of congenital cleft palate 
are, it is clear from the foregoing facts, partly of an embryogenetic nature, 
which is connected with ossification evolution, which last in turn is involved 
in hypophysis development. These factors are not necessarily connected 
with heredity, albeit the influence of maternal environment cannot be 
completely excluded. The influences checking palatal development must 
be present very early in embryogeny, since the palate ossification center 
is quite early in evidence. The factors affecting this ossification center may 
entirely arrest ossification, may arrest it irregularly, or may merely arrest 
its potentiality. In the latter case improved maternal environment has 
favorable results. In hereditarily defective cases, however, there is an 



A STUDY IN DEGENERATIVE EVOLUTION 301 

irregularity of balance giving an undue sway to certain early acquired 
structures at the expense of others later acquired which leads to increased 
irregularity, rather than its disappearance. The influence of hypophysis 
extracts on deficient osseous development is as yet merely suggested. 
Sufficient is known, however, to indicate that it might be well to use 
hypophysis extract in cleft palate on the possibility that the arrest was 
merely an arrest of potentiality, not an arrest of growth. 

Summary 

The development of face and jaws is influenced, on the one hand, 
by the sacrifice of these structures to brain gains, and on the other, by 
atavistic reversions to primitive types. 

In this struggle foi existence the points of ossification feel the greatest 
strain, among which are the palatal bones. 

Cleft palate is due to congenital and embryonic causes, and is either 
complete or partial. The complete variety involves the whole structure, 
from uvula to alveolar process, including even the lip (harelip). 

Congenital causes consist in disturbances of nervous poise which 
strengthen passing structures at the expense of later ones. 

Interference with palate formation, necessarily beginning early in 
embryology, indicates profound parental defects, operating through the 
pituitary body of the fetus. 

While heredity is an important factor, there is no evidence of direct 
heredity, i. e. of transmission of cleft palate in itself. It rarely, if ever, 
results from maternal impressions. 

Cleft palate is relatively or mion among the offspring of mentally 
defective parents. It occurs in animals in captivity but is not observed 
among wild animals. 

Arrest of ossification is the chief determining factor, and as atavism 
hastens ossification, giving it an impetus to outride periods of stress, it 
usually aids rather than hinders palate formation. 

The relation of vault deformities to cleft palate is that of hypertrophy 
— which is an expression of trophic instability. 

The permanency of the palate as compared with the turbinate and 
maxillary bones usually causes the palate to survive in struggles for nutri- 
ment, but parental low vitality (especially maternal) may so affect the 
palate as to give the other two bones the advantage. 

Considering the part played by the pituitary body, and on the assump- 
tion that the defect is only an arrest of potentiality, the administration of 
pituitary extract in cleft palate might be advisable. 



Chapter XXV 
THE VERTEBRATE TEETH 

Phylogeny and Ontogeny 

THE teeth, in their phylogeny from the placoid scale through fish, 
reptile, bird and mammal, exhibit many common characteristics. 
It is the intention here to simply mention such points as are of 
interest in the study of dental phylogeny and ontogeny. According to 
Owen, fish teeth in whatever relation they may be considered, whether 
in regard to number, form, substance, structure, situation or mode of 
attachment, undergo more striking modifications than do those of other 
vertebrates. 

Teeth of Fish 

Fish teeth are modifications of the placoid scale, namely horny plate, 
cone, prism or cylinder. Conical teeth are the most numerous and are 
slender, sharp, blunt or prominent. The great variety of forms renders 
them useful for many purposes. 

The skin of those fish which are covered with spines blends with the 
mucous membrane at the lips and turns in over the jaws. These spines, 
or placoid scales (Fig. 227) , grow in the dog fish (Fig. 228) and become 
larger than on the body surface. 

The first of the dermal skeletal parts are the scales of fish which differ 
from the epidermal scales of reptiles and mammals (turtles, alligators, 





Dermal papillae of Monacantbus trossulus. 




Dermal papillae of Monacanthus hippocrepis (magn. ) 

Figure 227 
Spines or placoid scales (Hertwig). These scales or plates may be situated upon the outer 
surface of the skin or mucous membrane of the mouth. They are modified, however, 
in shape in different vertebrates. 

302 



A STUDY IN DEGENERATIVE EVOLUTION 303 




Figure 228 
Transverse section of lower jaw of dog fish (Tomes), a, oral epithelium; b, oral epithelium 
passing on to flap; c, protecting flap of mucous membrane (thecal fold): d, youngest 
dentine pulp; e, youngest enamel organ; /, tooth about to be shed; g, calcified crust of 
jaw. 




Figure 229 
Saggital section of placoid scale (Hofer). b, basal plate; d, dentine; p, pulp cavity; sch, 
enamel. This placoid scale is the genesis of tooth development. Note the broad base 
and highly developed vascular structure. 



.'504 



DEVELOPMENTAL PATHOLOGY 



armadillos, etc.). They may be traced back to the primitive form, the 
placoid scales of the Elasmobranchs (sharks, rays, etc.). These rhombic 
plates, bearing in the middle pointed spines, are called dermal teeth, from 
their similarity in structure and development to the teeth of the mouth 
cavity (Fig. 229). They consist of dentine (d) and have a large pulp 
cavity (p) with numerous blood vessels. Whether the thin layer (sch) 
covering the tip can be called enamel is a question not yet decided. Der- 




FlGURE 230 
Teeth of Port Jackson shark (original). Primitive organs of the skin widely developed over 

the surface of the jaw. 




Figure 231 
Upper jaw of Port Jackson shark (Owen). The teeth in front are pointed; the larger in the 
middle for grinding purposes. The small teeth at the back part of the jaw are young 
teeth not yet in use. 






A STUDY IN DEGENERATIVE EVOLUTION 



305 



mal teeth and true teeth are identical structures, which, because of different 
position and consequent variation of function, have developed differently. 
Shark Teeth (Fig. 230) are nothing more than highly developed 
spines on the skin, which leads to the belief that teeth, in their phylogenetic 
development and structure bear similar relation to the primitive structures, 
namely spines, horny plates and placoid scales (Fig. 231). These spines, 
horny plates or placoid scales upon the surface are imbedded in tough 
mucous membrane (Fig. 232) and never acquire a bony connection. The 
teeth or placoid scales are nourished by nerves and blood vessels spreading 




Figure 232 

Horny tooth of Bdellostoma (Beard). D, calcified dental cap; e, enamel; h, horny tooth; 

he, epithelial groove in which the base is formed. 

out upon the entire under surface. There is, thus, the highest possible 
source of nourishment in this primitive tooth. 

Attachments of fish teeth present a greater diversity in mode, as well 
as place, than is observed in other vertebrate classes. The most common 




Figure 233 
The lower jaw of sheep's head, sargus ovis (original). Shows teeth in front and horny plates. 

over surface of jaw. 



306 



DEVELOPMENTAL PATHOLOGY 



mode is the cutaneous (Figs. 233 and 234). The teeth of the salarias are 
simply attached to the gum. Some species have a hollow space, supported 
upon bony eminences arising from the socket base like feline tribe claws 




Figure 234 
The upper jaw of sheep's head, sargus ovis (original). Shows teeth in front and horny plates 

over surface of jaw. 

(Fig. 235). When they are attached to the fibrous tissue covering the 
cartilaginous jaw, they are called hinged teeth (Fig. 236). Ossification 
between the dental pulp and the jaw takes place in some species. The 




Lower jaw of an eel (Tomes). 



Figure 235 
a, bone of jaw; b, bone of attachment; d, dentine;/, enamel; 
/, space vacated by shed tooth. 



tooth, prior to completion of ankylosis, is connected by ligamentous 
substances either to plain surfaces, eminences or shallow depressions in 
the jaw bone (Fig. 237). Sometimes, the side and not the end of the base 
of the tooth is attached by ankylosis in the alveolar border. In a few 



A STUDY IN DEGENERATIVE EVOLUTION 



307 



instances, the teeth are implanted in grooves and pockets to which they 
are attached only by surrounding soft parts, as in the case of the sawfish 




Figure 236 
Hinged tooth of pike (Tomes). A, dentine; b, elastic rod formed of uncalcified trabeeulae 
which might have become bone; c, hinge not itself elastic; d, bone of attachment; e, 
bone of the jaw. 

rostral teeth (Fig. 238). The incisors of the filefish also afford this curious 
example of gomphosis. In other fish varieties, where long, powerful, 
piercing, lancinating teeth are necessary for strength, the broad base of the 
tooth is divided into a number of long, slender, cylindrical processes, 
implanted, like piles, into the coarse osseous substance of the jaw. Often- 




Lower jaw of haddock (Tomes) . 



Figure 237 
a, bone of jaw; b, bone of attachment; d, dentine of 
tooth. 



308 



DEVELOPMENTAL PATHOLOGY 



times, the tooth substance is more dense than the jaw bone. Teeth 
implanted in sockets are found in the Barracuda pike, the filefish and 
other species. These teeth are developed and shed continuously, as in 
other classes. 

The Number of teeth varies widely from the edentulous fish upward. 
The sturgeon is without teeth as are also the pipe fish and sea horse (hippo- 
campus). In some of the lower types (the glutinous hag) a single tooth 



Jt' 



Figure 238 
Rostrum and under side of head of a small pristis (Tomes). 

the rostral teeth. 



a, mouth; b, rostrum; c, one of 



developed on the median line of the palate represents the dental system. 
In the carp, a single median tooth above the pharynx opposes two denti- 
gerous plates below. In the ceratodus, the jaws have four teeth, two 
above and two below. From these types are traceable every gradation 
in the progressive multiplication of the teeth, up to the pike, silurus, and 
other types, where the mouth contains many teeth. 

The Medullary Canals, or tooth pulps, also have undergone changes 
in evolution from the placoid scale. The tooth, assuming a different 
shape, still retains a large surface for the entrance of nerves and blood 
vessels. Although the attached surface has diminished in size, the inner 
tooth surface receives plenty of nourishment from the pulp, the largest 
diameter of which is at the base of the tooth. Changes in pulp size depend 
upon the size and shape of the tooth. 



A STUDY IN DEGENERATIVE EVOLUTION 309 

Development of fish teeth, as in all vertebrates, is produced by a 
single papillae from the free surface of either the soft, external integument, 
as in young pristis (sawfish), or of the mucous membrane of the mouth. 
In these primitive papillae, there can be readily distinguished a cavity 
containing fluid and a dense membrane surrounding the canal, itself 
covered by a thin, external buccal membrane which becomes thinner and 
thinner as the papilla increases in size. Some species have edentated 
horny plates arranged in greater or smaller rows and attached only to the 
mucous and fibrous membrane covering the maxillary cartilages. In 
others, the dental papillae do not sink into the substance of the vascular 
membrane. In still others, the papillae become buried in the membrane 
from which they arise. 

In all fish types, the teeth are shed and renewed throughout life, so 
that they can hardly be said to possess permanent teeth. The rostral 
teeth of the pristis (sawfish, Fig. 238) are the only exception. They may 
be regarded rather as modified dermal plates. 

Teeth of Reptiles 

The teeth of reptiles present less diversity in shape, attachment, 
number and development than fish. 

The Shape of reptile teeth is nearly always conical, never branching 
into cusps or roots at the tooth base. They may be sharp, blunt or serrated. 
In the carnivora, they are sharp and thin, while in the herbivora, they are 
blunt. 




Figure 239 
Lower jaw of lizard (Tomes), a, foramina leading to cavities of reserve. 

The cartilaginous tadpole jaws possess tough, horny plates simulating 
the shape of a turtle 's beak and also in addition, the inner edges of the lips 
have small horny spines or hooks each on its own individual base, which 
are shed before the commencement of true tooth formation. 

Lizards have the greatest variety of shape, some sharp at the edges, 
others rounded and blunt (Fig. 230) . 



310 



DEVELOPMENTAL PATHOLOGY 



In the saurians, the teeth are always conical, either sharp, blunt or 
serrated, with vertical ridges and prominences. 

Attachment. The mode of attachment of reptile teeth closely 
follows their destined use, governed by the habits of the type, and 
is similar to that of fish. Transitory human teeth bear a close analogy to 
reptiles. 

The most common attachment of reptilian teeth is ankylosis, some- 
times, however, merely in grooves, prominences, slight depressions or 
sockets. Saurian reptiles (lizards, etc.) have simple teeth attachment 
to the jaw margin. 

In the extinct Ichthyosaurus (fish-lizard), the teeth were not in 
distinct sockets but lodged in a continuous shallow groove with little or 
no transverse divisions. 

In the frog, the teeth are attached by ankylosis to a bony prominence 
for each individual tooth similar to Fig. 235. 

In the Dinosauria, the teeth were set in imperfect sockets, the outer 
alveolar wall being higher than the inner. 

In some snakes, the tooth is so firmly attached to the jaw bone that 
the latter might be considered a part of the tooth, since it is completely 
lost with the tooth and develops again for the new tooth (Fig. 240) . 




Figure 240 

Section of tooth and portion of jaw of python (Tomes). Shows the marked difference in 

character between the bone of attachment and the rest of the bone. 

When the tooth is ankylosed by its outer side to an external parapet 
of bone, the creature is said to be " pleurodont " ; when by the end of its 
base it is attached to the summit of a parapet it is "acrodont. " 

In the crocodile, the most highly developed living reptile, the teeth 
are situated in distinct alveolar sockets and are not ankylosed to the walls. 



A STUDY IN DEGENERATIVE EVOLUTION 



319 



They are situated at the margins of the jaws and are noted for their sharp- 
ness (Fig. 241). 

Number. Many reptiles, notably the toads, are entirely edentulous. 
Tortoises and turtles also have no teeth but the jaw margins have horny 
plates, shaped according to the animal's habits. In Rhamphorhynchus, 
the anterior ends of the jaws are without teeth, and it has been conjectured 
that these portions were sheathed in horny beaks. Prof. Marsh found 
several species of Pterodactyls wholly without teeth. The jaws, more like 
birds than reptiles, show no trace of teeth, and the premaxillaries seem to 
have been encased in a horny covering. Frogs have no teeth upon the 
lower jaw. The adult Hatteria (lizard-like reptiles) actually masticate 
upon the jaw bone, the teeth (rudimentary) having been worn away in 
early life. 

In some reptiles, there are as few as sixteen teeth in the upper and 
fourteen in the lower jaw. In certain batrachians, there are eighty in 




Figure 241 

Jaws of the crocodile (Tomes). The first, fourth and eleventh teeth in the lower jaw and 

the third and ninth in the upper are seen to attain to a larger size than the others. 



each lateral maxillary. The teeth in the different species and genera 
differ from each other in number. Some have sixty-six, others sixty- 
eight, some seventy-six and still others one hundred and eighteen. 

The Medullary Canals, or pulps of the teeth of reptiles, are not 
unlike those of fish. Beginning with the broad surfaces of the plates and 
horny teeth, in which the entire surface furnishes nerves and blood vessels 
for their nourishment, the canals change with the change in the shape of 
the tooth. These pulps extend into the tooth substance, but always remain 



312 



DEVELOPMENTAL PATHOLOGY 



largest and broadest at the base, as observed in the crocodile. In all 
sauropsidae, the foramina are large (Fig. 242). 

Development. In the development of reptilian teeth, a period 
occurs when the primitive dental papillae are not protected by either an 
outer or inner alveolar process. In another stage, the groove containing 




Figure 242 
I. Section of premaxillary bone of reptile showing attachment (Hertwig). Magnified 22 
times. II. Dentine and enamel, magnified 500 times. III. Enamel, magnified 500 
times. A, Blood vessel of the pulp cavity. C. Crusta petrosa. D. Dentine. F. 
Processus dentalis. H. Layer of epithelium. 0. Tooth cuticle. R. Second tooth 
germ. S. enamel. X. Cutaneous glands. 

the dental germs is protected by a single extended cartilaginous alveolar 
ridge, as in most lizards. Next in order of evolution there is developed an 
internal alveolar plate, and the sacs and pulps of the teeth sink into a deep 
but continuous groove in which traces of transverse partitions soon make 
their appearance. In the Ichthyosaur, the relation of the jaws to the 
teeth advances beyond this stage. Finally the dental groove is divided 
by complete partitions and separate sockets are formed for each tooth. 
This developmental stage is attained in the most highly organized reptiles, 
represented by the crocodile. 

In crocodile tooth development, absorption of the roots of the first 
teeth takes place, allowing the second to take its position. The number 
of teeth does not change. The young crocodile possesses as many teeth as 
the adult. The development of a new tooth precedes the absorption of 
the older tooth root (Fig. 243) . In this manner, there is a tooth succession 
throughout the life of the animal. 



A STUDY IN DEGENERATIVE EVOLUTION 



313 



The jaws and teeth of fish and reptiles are of interest, since, as has 
been already shown, one form of degeneration of the human jaw, the V- 
shaped dental arch, assumes these types. 




Figure 243 
Section of Jaw of young alligator (Tomes). A, oral epithelium; b, bone of socket; d, dentine 
of old tooth; 2, tooth next in order of succession which is causing absorption of one side 
of the base of the old tooth; 3, young tooth germ. 



Teeth of Extinct Birds 

"Birds," says Prof. Huxley, "are animals so similar to reptilia in all 
the most essential features of their organization, that they may be said to 
be merely an extremely modified and aberrant reptilian style. Their 




Figure 244 
Head of extinct bird. Natural size. (Dames). Shows individual cone-shaped teeth. 



314 



DEVELOPMENTAL PATHOLOGY 






differentiation is, however, so great as to indicate without doubt, their 
rights to form a distinct class. " 

Since birds belong to the same group as reptiles (sauropsidae) it would 
be strange if the teeth of both did not resemble each other. 

Many years ago, Geoffroy St. Hilaire described a series of vascular 
pulps on the margin of the jaw of parakeets about to be hatched which, 
though destined to form a horny bill and not to be calcified into teeth, 
strikingly recall dental pulps. The famous fossil bird of the lithographic 
shale of Bavaria had a long jointed tail and possessed teeth (Fig. 244). 
Up to the discovery of this bird's head, toothed birds had been unknown. 
Later, however, Prof. Marsh found nine genera and twenty species. They 
are referable to two widely different types. One group consists of a very 




Figure 245 
Skeleton of the Hesperornis regalis (Marsh). The long bony tail shows a relationship to the 
reptilian type. The teeth are not unlike those of reptiles. The undeveloped [wings 
show that the bird was a diver. 



A STUDY IN DEGENERATIVE EVOLUTION 



315 



large swimming bird without wings, having teeth in grooves (Odontocae 
type, genus Hesperornis) . The other group consists of comparatively 
small birds with great power of flight and having their teeth implanted in 
distinct sockets (Ondontotornae, of which the genus Ichthyornis is a type) . 

The genus Hesperornis (probably diving birds, Fig. 245) includes 
species six feet in length. The teeth are not implanted in distinct sockets, 
but lie in a continuous groove like those of the Ichthyosaurus. The slight 
projection from the lateral walls indicates a partitioning off into sockets, 
but nothing more than this is attained, and after the soft parts perish, 
the teeth are easily displaced and had often fallen out of the jaws. The 
premaxillary is edentulous, but the teeth extend quite to the anterior 
extremity of the lower jaw. In one specimen, there are fourteen sockets 
in the maxillary bone and thirty-three in the corresponding lower jaw. 

The successional tooth germs formed at the side of the base of the 
old ones and caused absorption of the old roots. They migrated into 
the excavations so formed, grew large and ultimately expelled their pre- 
decessors (Fig. 246). In structure, their teeth consisted of hard dentine, 




Figure 246 

Tooth of Hesperornis regalis (Marsh). Enlarged eight diameters. The successional tooth 

is immediately underneath, producing absorption of the tooth above. 



invested with a rather thin layer of enamel and a large axil pulp cavity. 
The basal portion of the roots consists of osteodentine. The outer side of 
the crown is nearly flat, the inner strongly convex. The junction of these 
surfaces is marked by a sharp unserrated ridge. 



316 



DEVELOPMENTAL PATHOLOGY 



In Ichthyornis (Fig. 247) the teeth were about twenty-one in number 
in each jaw, sharp and recurved. The crowns were coated with enamel. 
The front and back edges were sharp but not serrated. They were im- 
planted in distinct shallow sockets but the maxillary teeth were a little 
larger than those opposing them. The premaxillaries were evidently 
edentulous and perhaps composed of a bony bill. In the lower jaw, the 




Figure 247 
Skeleton of Ichthyornis victor (Marsh). Although the tail is made up of bony joints, it is 
shorter than the previous illustration and possessing wings and short legs shows a much 
higher type of bird. The teeth are specialized with single cones and separate sockets. 



largest teeth were about at the center, those at the posterior end being 
smaller, the sockets deeper and stronger than in the upper. Tooth suc- 
cession took place vertically. 

According to Prof. Marsh, the main features of the teeth of the Hes- 
perornis are characteristically reptilian. One of the earliest of these 
fossil birds, the Archaeopteryx, is a remarkable combination of bird and 



A STUDY IN DEGENERATIVE EVOLUTION 317 

lizard. Unlike any modern bird, the jaws were provided with many 
conical reptile-like teeth situated in distinct sockets. 

With these notable exceptions, the jaws of all known birds are tooth- 
less, the horny cases forming their beaks taking the places and fulfilling 
the functions of teeth. 

The relation which the horn cone bears to the dental papilla and its 
dentine is entirely different from that borne by the horny teeth of the 
ornithorhynchus,. whose horny plate lies beneath the teeth. This is a 
phenomena of evolution by atrophy through which structures disappear, 
by the law of economy of growth, for the benefit of the organism. The 
evidences that true teeth may become replaced by horny teeth, these 
again coalescing with their neighbors to form a horny casing, have been 
set forth. 

It would seem, then, that the precursors of birds had true teeth. It 
is probable that a sufficiently extended search will reveal rudimentary 
teeth surviving beneath the functional horny bill, or even above it, like 
those of the ornithorhynchus. Indeed, Rose has found that in Sterna the 
tooth band exists, although no rudiments are to be found of tooth germs. 

Teeth of Mammals 

In all essential characters by which mammals are distinguished from 
other vertebrates, such as possessing warm blood, breathing air by lungs, 
bringing forth their young alive and nourishing them for a time with milk, 
they agree with other members of their class. 

All mammalian dentition consists of a definite set of teeth, nearly 
always constant and of determinate number, form and situation. With 
but few exceptions, they persist in a functional condition throughout the 
animal 's life. In many species, the animal possesses only one set of teeth, 
the set first formed being permanent, or, if lost, never replaced. No mam- 
mal has, normally, more than two sets of teeth. When the first teeth are 
well developed and continue in place during the greater part of the animal 's 
growth (as is especially the case with the ungulata and to a lesser degree 
with the primates and carnivora), the use is obvious, since they form, 
structurally, a complete edition on a small scale of the more numerous and 
larger permanent set. Those animals, therefore, that have well developed 
and tolerably persistent first teeth may be considered in a higher state of 
dentition development than those that have the first set absent or rudi- 
mentary. 

Mammal dentition is of two kinds. In some few forms, known as 
"homeodont" all the teeth are of one type or pattern; for example the 
sloths, armadillos, dolphins, etc. The remainder, or "heterodont" mam- 



318 



DEVELOPMENTAL PATHOLOGY 



mals, forming the great majority, are provided with teeth of several differ- 
ent types. In the dog's skull (Fig. 248) the three small teeth fixed on each 
side in the premaxilla (pmx) are the incisors, or cutting teeth (1); next 
follows a long and powerful tooth, known as the canine (c). Behind this 
there are four cutting edged premolars (pm), and two flattened true molars 
(m). In the lower jaw, the same tooth types are represented, there being 
in the dog three incisors, one canine, four premolars and three molars. 
Tooth numbers vary greatly in the different mammal orders. 

A second mammalian dental division is, in some few forms, chiefly 
"homoedont," where there is only a single set of teeth, while in others a 
permanent set is preceded by an earlier temporary one, only present during 




pmx. 



Figure 248 

Skull of dog divided down the center to show internal structure (Sir W. H. Flower), i, three 

incisor teeth making six on each jaw; c, canine teeth; pm, premolars; m, molar teeth. 

the period in which the young animal is nourished by milk, although its 
duration does not always coincide; the temporary teeth, in some instances, 
are shed or absorbed by the time the animal is born. 

The teeth belong, essentially, to the dermal organ system, passing 
from hard spines and scales upon the integument covering the outer sur- 
face of the body in the lower vertebrates. In mammals, they are special- 
ized, limited in localities, and imbedded in the alveolar process bordering 
on the upper and lower jaws. 

The Monotremata (lowest mammals) lay eggs, have a cloaca, and 
are without nipples, the milk exuding from pores in the skin. The temp- 
erature is lower than other mammals. Recent observations show that the 
temperature of the echidna stands only at about seventy-eight degrees, 
some twenty degrees lower than man, and about thirty degrees below the 



A STUDY IN DEGENERATIVE EVOLUTION 



319 



average bird. The study of these animals is interesting, since they form 
the connecting link in tooth development and other states between the 
cold and warm blooded animals. The skull is long and depressed; there 
is a large, rounded, brain case with thin walls, as in birds. There are no 
true teeth in adult life. In the young duck-bill (ornithorhynchus paradox- 
us) are three flattened saucer-like teeth in each half of the jaw, which are 
shed and replaced by projections or cornules. The adult duck-bill (orni- 
thorhynchus paradoxus, Fig. 249) has a broad flat rostrum, forked in 




Figure 249 
The Ornithorhynchus or Australian duck-bill (British Museum Guide to Mammalia). An 
egg-laying mammal with pouches. There are no true mammae, the milk oozing from 
the pores of the skin. It first has teeth, afterward horny plates develop. 

front, which supports the beak and in which the teeth first, and later the 
cornules, are implanted. In the echidna the snout is long, narrow and 
toothless, forming a long tube for lodgement of the tongue, as in the true 
ant-eater (echidna acaleata, Fig. 250). In the proechidna, the snout is 




Figure 250 

The common Echidna or Ant-eater (British Museum Guide to Mammalia). It has a long, 

narrow snout without teeth but plates with horny spines serve their place- 



320 DEVELOPMENTAL PATHOLOGY 

nearly twice as long as the brain case. The palate of the echidna is covered 
with rows of horny spines which scrape the ants off the tongue when it is 
drawn into the mouth. The ornithorhynchus muzzle resembles a duck's 
bill and is provided with cornules that take the place of the true teeth. 
The upper teeth have broad-topped crowns with two long cusps on the 
inner edge, and a serrated border along the outer edge with many small 
cusps. On the lower, this is reversed. They have low, broad crowns 
with short stunted roots, which are for a time rather firmly held. They 
are on the top of the horny plates. The expanded crowns narrow rapidly 
at the neck and are surrounded by a very dense, thick epithelium, almost 
horny, that rises into a ring around them and dips underneath the expanded 
portion so that the crown lies in a special cup of horny consistency. 

This cup is not complete at the bottom, but the roots pass through it 
and fit bone depressions perforated by the foramina for vessels and nerves. 
When the animal is about twelve inches long, the teeth are shed and horny 
cups grow in, underneath, and become complete. The peculiar carved 
horny plate surface has its form determined by forming the bed for a tooth 
with several roots. Although the horn grows underneath and fills up the 
holes for the roots to go through, yet the old form is maintained by the 
horny plate, which henceforth serves for mastication. 

Horny plates are not to be considered as horny teeth, for they are 
epithelial structures, that take the place of teeth. They are, hence, not 
closely homologous with the horny teeth of lampreys and myxincids 
(hags). The true teeth consist of a body of dentine with a central pulp 
capped with thin hard enamel and implanted by short roots, the breadth 
of crown exceeding its certical dimension. The enamel is of simple struc- 
ture. The dentine is permeated by the fine dentinal tubes with a number 
of interglobular spaces, which partly covers the tubular structure of the 
crown. In the principal cusp apparently vascular canals exist. Toward 
the stunted roots a somewhat abrupt transition in structure takes place. 
All dentinal tubes disappear and large lacunae appear. The roots are of 
softer, coarser material than the crown, which is itself not a high type of 
dentine structure. The root type of the ornithorhynchus (duck-bill) and 
that of the hesperornis (extinct toothed bird) resemble each other. 

The Cetacea are water animals. Outwardly they resemble fish, 
but their entire structural organization places them in the mammalian 
class. They have mammae; they breathe by lungs; they have a heart 
with two ventricles and two auricles. Instead of being organized for 
living on land, like mammals, they are admirably adapted for the water. 
Their body, more or less pointed, terminates in a broad transversal fin- 
like tail, unlike the vertical tail of fish. The tail is the principal agent in 
locomotion. On the back of most cetacea there is a dorsal fin which is 






A STUDY IN DEGENERATIVE EVOLUTION 321 

only a skin modification. The cetacea have no posterior limbs; their 
anterior limbs are swimming paddles, of comparatively little use for loco- 
motion and merely act as ballast. Their anterior limbs are essentially 
of the same structure as the corresponding limbs of other mammals; namely 
the bat's wing, the dog's paw, man's limbs. Prominent in this order are 
the whales and dolphins. 

Whales may be divided into two classes, Odontoceti, or tooth whales, 
and Mystacoceti, or baleen whales. One important anatomic character 
is that the Odontoceti have no baleen, or whalebone, but possess teeth 
which are sometimes numerous, sometimes few or quite rudimentary in 
size and function. 

The narwhal present the most peculiar dentition of any mammal. 
In the adult, there are only two teeth (cuspid), both of which lie in the 
upper jaw horizontally. In the female, these remain permanently hidden 
in the jaw bone so that this sex is practically edentulous; in the male, 
however, the right tooth remains similarly concealed and abortive, showing 
the law of arrest of development and compensation. The left is excessive- 
ly developed, often equalling in length more than half the animal and 
projects horizontally from the head in a cylindrical form. The surface is 
sculptured by grooves and ridges. 

The so-called "whalebone" whales (Mystacoceti) possess rudimentary 
teeth in early life, but they are soon lost and their places are taken, in 
the upper jaw, by the baleen (whalebone). 

Baleen, or whalebone, is similar in development to the cornules of 
the ornithorhynchus (duck-bill). Each plate is developed from a vascular 
persistent pulp, which sends out numerous long thread-like processes that 
penetrate far into the hard substance of the palate. Each hair-like fiber 
has within its base a vascular filament or papilla and, in fact, is nothing 
but an accumulation of epidermic cells concentrically arranged around a 
vascular papilla, the latter being enormously elongated. The baleen 
plate is composed mainly of these fibers, which constitute the hairs of its 
frayed-out edge. In addition to this, layers of flat cells bind the whole 
together and constitute the outer or lamellar portion. The whalebone 
matrix produced by cornification of the epithelial covering of papilla is an 
epithelial epiblastic structure, morphologically corresponding, not with 
dentine, but with enamel. The whole whalebone plate and the vascular 
ridge and papilla which form it are comparable to the strong ridges upon 
the plates of certain herbivora. Study of the mouth of young whales prior 
to the cornification of the whalebone tends to demonstrate this. This is 
obviously a return to the placoid scale type, carried into the interior by 
the mouth changes. The development recalls that of the spines on the 
palate of the echidna. 



322 DEVELOPMENTAL PATHOLOGY 

The Sirenia (manatees and dugongs) are herbivorous water mammals. 
Manatee dentition comprises two rudimentary incisors above and two 
below, buried under the horny plates occupying the anterior of the mouth. 
The animal possesses as many as forty-four molars, not, however, all in 
place at one time. The anterior ones are shed before the posterior come 
into place. 

The dugong (sea cow) possesses a single deciduous tooth which appears 
before the incisive tusk. It is still undecided whether this be rudimentary 
or temporary. In either case, it is a lower vertebrate degeneration. The 
animal has two tusks imbedded deeply in the alveolus. In the female, 
the tusks (incisors) do not project beyond the gum, their pulp cavities are 
closed, and the investment of enamel is complete over the top of the tooth. 
These rudimentary abortive teeth are removed by absorption. They are 
covered by the dense, horny plates clothing this part of the jaw. These 
teeth are without function. Behind the region covered by the horny 
plates, the dugong has five molar teeth on each side consisting of dentine 
and cementum only. 

Ungulata teeth vary considerably according to the animal 's habits and 
methods of obtaining food. Prominent in this class are the ruminants. The 
dental formula in some of these animals is represented by three incisors in 
each jaw, one cuspid, four premolars and three molars, making forty -four 
teeth in all. The horse retains the full mammalian number of teeth. These 
teeth have roots imbedded in the alveolar process. In other ungulata, 
the incisors upon the upper jaw are either in a degenerate condition or are 
entirely missing. The hollow horned ruminants (sheep, oxen, cows, 
antelopes) and, likewise, almost all of the solid horned ruminants (deer) 
have this degeneration. Not a few of this group are without canines 
upon the upper jaw. Six incisors on the lower jaw show again the law of 
compensation. The upper canines, when present, are, with the notable 
exception of Moschus, Elaphodus, Cervulus and Hydropotes, small later- 
ally-compressed rudimentary teeth. Their crowns are in about the same 
stage of reduction as the crown of horse canines, but their roots are relative- 
ly much more reduced. Hence they are often lost in dried skulls and it 
has generally been supposed that but few deer possessed canines at 
all. The roots of the teeth of the horse stand midway between those 
teeth which have persistent pulps without roots, like the elephant, rodents, 
etc., and those of mammals with perfectly formed roots. Thus the teeth 
of the horse possess open roots with persistent pulps until about the fifth 
year of age. 

Rodentia dentition is represented by four incisors, two above and 
two below with three molar teeth on each jaw. The rodentia are character- 
ized by want of cuspid teeth and by peculiar structure and great develop- 



A STUDY IN DEGENERATIVE EVOLUTION 323 

ment of their incisors. These teeth are large and curved, possessing per- 
sistent pulps which allow the teeth to elongate. The pulp canals are large 
and are the width of the tooth. They are admirably suite for gnawing, 
in that they have sharp, chisel-like edges, consisting of a hard outer enamel 
coat on their frontal surfaces which wears more slowly than the soft dentine. 
These teeth grow continually from their base as fast as the tips wear down. 
In case one be lost, the opposing tooth continues growing until it prevents 
the mouth 's closing, causing starvation, or curves over and enters the back 
of the head, in this manner bringing about the animal's death. 

In this mammalian class, a most extraordinary condition is observed 
in that the molar teeth have close roots when completely developed and 
do not elongate, while, on the other hand, the incisors grow with their 
persistent pulps. All the teeth are implanted in the alveolar process. 

The Insectivora have small brains and faces, some resemble rodents 
and others lemurs. The galeopithecus (flying lemurs), formerly considered 
with the lemurs, form one group. One of their most peculiar features is 
to be found in the structure of their inferior incisor teeth, which is quite 
unlike those of any other mammal, or indeed of any animal. In both 
jaws these incisor teeth are expanded laterally and compressed from front 
to back, with a number of cusps on their summits, and those of the lower 
jaw have very wide, flattened crowns penetrated by a number of parallel 
vertical slits, so that they resemble small combs mounted upon narrow 
stems. Then again, the outermost of the two pairs of upper incisor teeth 
as well as the upper tusk or canine (which is nearly similar to the incisors) 
are inserted in the jaws by two distinct roots. This is a unique feature 
among living mammals, although the moles and hedgehogs have two 
roots to their upper tusks. The other insectivora are of two groups known 
by the molar pattern. The majority have a W-patterned crown, while 
others have narrower molars of a V-pattern. 

The insectivorous bats have small incisors, rather large cuspids and 
molars of the W-pattern. 

The lemurs usually have the upper incisors very small and invariably 
separated. In the cheiromys (aye-aye) the incisors form a single pair of 
large, curved teeth, growing from persistent pulps and wearing obliquely, 
so as constantly to preserve a sharp, cutting edge. The enamel is very 
much less thick, yet not altogether absent upon the backs of the upper 
incisors. The lower incisors, narrow from side to side and thick from 
back to front, are composed largely of enamel, the dentine constituting 
only a small part. Directly behind the incisors is a space devoid of teeth 
and then follow four upper and three lower teeth, not of persistent growth 
and having definite roots resembling the molars of many omnivorous 
rodents. The lower incisors are unique and of a remarkable pat- 



324 DEVELOPMENTAL PATHOLOGY 

tern. They are finely serrated and so deeply notched as to appear 
like combs. 

The Carnivora include the strongest and most formidable flesh- 
eating mammals, known as beasts of prey, such as cats, wolves, dogs, bears, 
weazels, etc. There is another type, suited for water life, whose limbs are 
modified into swimming organs, namely seals and walrus, etc. All in- 
dividuals of this order, though subsisting in part upon animal matter, do 
not live upon it exclusively. Some have added a vegetable diet in different 
proportions. Indeed many are more herbivorous than carnivorous. 
Hence variations of greater or lesser degree must take place in their ali- 
mentary tract, especially the digestive canal and dentition. These modi- 
fications form very important characteristics, whereby the various types 
are classified. 

The dental system of the carnivora consists, as a rule, of incisors, 
canines and molars. There are six incisors in each jaw. The canines are 
long, strong, sharp, and well suited to tear the victim's flesh. There are 
two in each jaw, placed on each side of the incisors; there is generally a 
space between the incisors and canines of the upper jaw for the reception 
of the lower canine. The molars vary in number and form, according to 
the kind of food; they are divided into front molars, flesh teeth and tuber- 
cular or back molars. The front molars are usually pointed and increase 
in size from the first to the last; there is at least one, and four at most. 
These are followed by a tooth with a sharp edged crown, the largest in the 
whole system, known under the name of flesh tooth. The last or tuber- 
culated molars, thus called on account of their large and flattened crown, 
are sometimes entirely wanting on the lower jaw, where they are always 
fewer than on the upper jaw. 

The flesh and tubercular teeth vary, not only as to structure, but 
also in the act of mastication. The flesh teeth alternate in their action, 
like the blades of a pair of scissors, eminently fitting them to cut and 
divide flesh. The tuberculated molars, on the other hand, being directly 
opposite each other, and articulating closely, crown to crown, are well 
suited for grinding. 

It may be inferred, then, that an animal is carnivorous in proportion 
as the flesh teeth are more and the tubercular teeth less developed, and 
omnivorous (mixed eating) when these conditions are reversed. We may, 
therefore, say with Isidore Geoff roy Sainte-Hilaire, ''that the exact extent 
to which an animal is carnivorous is defined with an almost mathematical 
accuracy by the modifications of its dental system and especially of the 
flesh-teeth." 

The points of special interest in this order of mammals are the prom- 
inence and size of the canine tooth — six incisors instead of four as in 



A STUDY IN DEGENERATIVE EVOLUTION 325 

man — and the shape of the jaws. As we have already seen, in neurotics 
and degenerates, one form of jaw (the saddle) deformity is arrest in phyto- 
geny at the carnivora stage. 

The Quadrumana (monkeys) are the highest of the mammals next 
to man. Their habits and physical organizations are more nearly like 
those of man than any of the other vertebrates. The gibbon, the orang, 
the gorilla and chimpanzee, the highest of the order, are only slightly 
inferior to the human species. From a purely anatomic viewpoint, they 
may be classed in the same genus. 

Like man, they stand upright; are without a tail; like him, they are 
provided with hands; the face is without hair; the eyes are directed for- 
ward, while the internal organs and brain are similar. The throat, larynx 
and tongue are analogous, but they are incapable of speech. 

The teeth are of the greatest interest at the present time. In some 
of the lower species (Galeopithecus, flying lemurs), there are thirty-four; 
namely, ten incisors, four canines and twenty molars. They have two 
incisors less above than below. The total number of teeth in the lower 
jaw is eighteen. The molars are studded with points like those of the 
insectivora. The lower incisors are directed forward and are deeply 
notched at their summits like the true lemurs. 

The Simiadae (true monkeys) are divided into the new and old 
world monkeys. The new world monkeys are the marmosets and the 
Cebidae (those having thirty-six teeth) . The marmosets have only thirty- 
two teeth, unlike the others which have thirty-six. They have three pre- 
molars on each side. The old world monkeys have the same dental for- 
mula as man. The anthropoid apes resemble man in their dentition. 
The Simiadae and Anthropoidae (except a generalized type found by Ame- 
ghino in the tertiary of Paraguay, which has rodent, insectivorous and 
ungulate features) are identical as to pulp with man. In all the essential 
points, the human teeth are not unlike the higher apes. 

The Shape of mammal teeth which are of a higher order of vertebrates, 
depends upon their jaw situation and the special function they are to per- 
form. The tooth shape also depends upon the food upon which the animal 
lives, and upon other purposes. They are incisors, canines and molars. 
In the carnivora, they are sharp and arranged in such a manner as to act 
like the blades of a pair of scissors. In the herbivora, they are flat and 
rough. In the insectivora, they are armed with little points which fit into 
each other. 

The simplest form of mammalian teeth on a large scale is the elephant 's 
tusk. It consists of a hard dentine mass, conical in shape, but during 
growth becomes more and more cylindrical or uniform in width; a thin 
enamel covering is observed upon the apex in the earliest condition but 



326 DEVELOPMENTAL PATHOLOGY 

soon disappears, a thin layer of cement covers the circumference of the 
tooth throughout life. 

The pulp is long and the width of the tooth, is imbedded deeply in a 
socket in the maxillary bone, and grows throughout life. At the outer 
surface, it is converted into dentine which causes the tooth to elongate 
continuously. Sometimes, it wears away slowly. Such teeth are "root- 
less" and have "persistent" pulps. 

The incisor teeth present many variations in shape, in order to fulfil 
their destined function. In all gnawing animals, they are much lengthened, 
somewhat curved and have sharp edges with only the front surface covered 
with enamel. In this class are the rodents, tillodonts, allotheriae and 
diprotodontic animals of prey. In pigs, the lower incisors grow horizon- 
tally upward and forward in order to obtain the roots upon which they 
live. The lower incisors of the lemuridous monkeys have finely serrated 
edges, while the sirenia have large upper incisor teeth for pulling up the 
water plants upon which they feed. 

When an incisor tooth develops excessively in size, the remaining 
incisors are few, for example, many animals belonging to the proboscidian 
low type have no lower incisors. The complete absence of upper incisors 
occurs in ruminantia, dinocerata and chalicotheridae. In many edentata 
both upper and lower incisors fail to develop. 

The canine teeth, so necessary to the carnivora for tearing their food, 
sometimes develop to a considerable degree, forming tusks, as in the wild 
boar, etc. The elephant and narwhal's tusks are elongated canine teeth. 

According to Dr. Charles Ward, there are "four well-defined types 
of molars" in mammals, as follows: 

"I. Haplodont type. The crown, undivided or simple. Existing 
toothed whales, some carnivora, edentates and certain rodents have teeth 
of this description. 

"II. Ptychodont type. The crown folded on the sides, the folds 
frequently crossing the crown. Most rodents bear molars of this type. 

"III. Bunodont type. Crown supporting tubercles. The molars 
of a few existing and many extinct ungulates, carnivores in general, and 
most primates, including man, are of this type. 

"IV. Lophodont type. The summit of the crown thrown into folds 
of transverse or longitudinal direction. The Lophodonts comprise the 
higher ungulates and some rodents. 

"The derivation of the bunodont from the haplodont type, by a 
development of accessory tubercles on the crown of the primitive tooth, 
and the gradual evolution of the lophodont type from the bunodont, are 
inferences toward which a study of the paleontological evidence inevitably 
leads. The highest stages of development to which the molar teeth have. 



A STUDY IN DEGENERATIVE EVOLUTION 



327 



attained are found among the terrestrial carnivora on the one hand and 
the higher ungulates on the other, both of which orders (together with the 
remainder of the Educabilia) are probably derived, as believed by Cope, 
from a bunodont ancestor, having plantigrade pentadactyle feet. In 
fact, the primitive bunodont type of molar characterized the mammals 
of the early Eocene period. But we ourselves are plantigrade, pentadactyle 
bunodonts. " 

Preiswerk classifies the molar teeth, which are found only in the 
mammalia, into, 

1. Teeth with sharp points and edges (secodont) Fig. 251 (a). 

2. Cuspid teeth (bunodont) Fig. 251 (b). 

3. Teeth with straight crests of enamel (lophodont) Fig 251 (c). 

4. Teeth with crescentic ridges on their crowns (selenodont) Fig. 

251 (d). 
An example of the molar tooth of animals which sever and tear their 
food, namely carnivora, marsupialia, chiroptera, insectivora. The molars 





Figure 251 
Mammalian molar forms (Prieswerk) . 



of the insectivora are approximately of this type. Meat nourishment is 
easily digested so the entire alimentary tract of these animals is simple. 
In carnivora, whose dental crowns are narrow and provided with sharp, 
horizontal edges, the intestinal canal is but from three to five times as 
long as the body, while the herbivorous animals possess an intestinal canal 
twenty times as long as their body. 

An interesting point in connection with the teeth of mammals is the 
fact that teeth with two or more roots are developed. In the lower verte- 
brate classes, such is not the case. 



328 DEVELOPMENTAL PATHOLOGY 

Sir W. Flower shows that the molars are larger in the lower races, 
where they may occupy on the alveolar arch the same compass as in the 
chimpanzee. That this relation has persisted from the remotest times 
is evident from the fact that in the "man of Spy" the molars increase in 
size posteriorly to the same extent that they do in the apes, which is the 
reverse of what is usual in man, where they diminish posteriorly, or in a 
few lower races (Australians, etc), remain equal. In this palaeolithic 
race the premolars approximate "the relative dimensions seen in the 
chimpanzee," while the third molar even exceeds that of the chimpanzee, 
"reminding one of some of the gibbons. " Thus may perhaps be explained 
the curious fact that, as noted by Dr. Houze, "the third molar is often as 
large as the others in the lower races," whereas, in Europeans, the last 
molar is disappearing through disuse, the jaws become contracted and 
orthognathism results. To this contraction are due some forms of the 
irregularities of the teeth in civilized man, since the small jaws cannot 
contain thirty-two well developed teeth. In savages, this defect seldom 
occurs, but supernumerary teeth have appeared among the New Caledon- 
ians, where Bertillon and Fontan have reported finding a fourth 
molar. 

The Use of teeth in the various orders of mammals may be classed 
as follows : 

First, in the beaver, as implements for transporting and working 
building material. 

Second, in elephants, muskdeer, etc., as aids in locomotion. 

Third, in dogs, for defense. 

Fourth, in orang, narwhal, as inflictors of wounds. 

Fifth, in wild boars, to defend their mates. 

Sixth, in man, for speech, as ornaments characterized for age and sex, 
for biting, seizing and crushing food or otherwise mechanically dividing 
solid materials by mastication so as to prepare it for digestion in the 
stomach. 

The Attachment of mammal teeth is not unlike that found in fish, 
reptiles and birds. The horny plates of the lowest mammals are situated 
upon the surface of the jaws with free blood and nerve supply. Ankylosis, 
or bone union, does not occur in mammals showing a step further advanced 
in evolution from fish, reptiles and birds. A vascular layer of connective 
tissue always intervenes. Lastly, but by far the most common teeth, 
are those with one, two, three or more roots implanted in corresponding 
distinct sockets in the jaw surrounded by alveolar process. 

The Number of teeth in the mammalia is not so varied as in the 
lower vertebrates. To begin with the simple cone tooth, each class, fish, 
reptile, bird and mammal-recapitulates each step in their phylogeny. 



A STUDY IN DEGENERATIVE EVOLUTION 329 

There is, however, a gradual improvement in shape, attachment, number 
and development in each class from a lower to higher development. 

Mammals, like fish and reptiles, include a few edentulous species. 
These are the anteaters, forming when clothed with hair, the genus myrme- 
cophaga; when covered by scales, the genus manis; when armed with 
spines, the genus echidna. 

In the felines, the tongue epithelium is thickened at the fore part of 
its dorsom and invests the papillae there, with hard sheaths like prickles 
which are analogous to the lingual teeth of certain fish and batrachians. 
The back of the dorsom of the tongue in the echidna is provided with 
horny plates, or denticles, which bruise the food against hard and prickly 
epithelium covering the palate. 

A few mammals have the jaws provided with horny substitutes for 
teeth, — as the whalebone whales (Balaena and Balaenoptera) and the 
ornithorhynchus (duck-bill), — in the rest of the class true teeth are present. 

Horny processes analogous to the palatal teeth of fish and reptiles 
are likewise developed upon the roof of the mouth of the great Bottlenose 
dolphin. 

If the monotremes, edentates and whales, in which there is marked 
degeneration in the dentition, be omitted, there are four particulars where- 
in the dentition of mammals is shown to be more developed than that of 
other vertebrates. (1) The number of teeth is constant for the species, 
usually for the genus and often for the family. As man normally has 
thirty-two teeth, so the dog has forty-two, the anthropoid apes thirty-two, 
the platyrhine (flat-nose) apes thirty-six. (2) The teeth are firmer. 
(3) The body of dentine is divided, by a slight constriction, into a crown 
covered with enamel and a root enveloped in cement (bony tissue). (4) 
The roots are placed in separate sockets (alveoli) in the jaws, and in those 
cases where continuous growth is necessary, the pulp persists and the 
teeth as in the incisors of rodents and tusks of elephants and pigs, grow 
indefinitely. The teeth of the horse, the ox and many other mammals 
have open pulp chambers. The teeth of rodents are for a time rootless 
and with open chambers, but ultimately the pulps contract at the necks 
and cease to grow long. Such teeth are said to be rootless, or to have 
persistent pulps. The teeth of man are quite different. After the crowns 
have fully formed by calcification of the germ, the pulp, although continu- 
ing to elongate, begins to contract in diameter. A neck of slight con- 
traction is formed and the remainder of the pulp is constricted in form 
at the neck. The remainder of the pulp is converted into the root in a 
tapering conical process, imbedded in the alveolar process of the bone, 
having at the extremity a minute perforation through which the vessels 
and nerves pass to maintain the vitality of the tooth, — a very different 



330 DEVELOPMENTAL PATHOLOGY 

state from the rodents, which have open cavities at the base of the growing 
tooth. When the teeth with closed foramina are worn away, the surface 
is never renewed. In teeth with open pulp chambers and growing pulps, 
the wearing surface of the teeth is replaced. The teeth of the horse, cow, 
ox and the tusks of the muskdeer and of the walrus have persistent pulps 
and are open at the base until the animal is advanced in age, when in some 
instances they close and the pulp ceases to be renewed. 

When they have attained their position in the jaw, human teeth can 
never increase in length or alter their position. If they appear to do so, 
in old age, it is because of interstitial gingivitis which causes them to move 
about and gives rise to root absorption. The open cavity at the base of an 
imperfectly developed tooth causes it to resemble the persistent condition 
of the rootless tooth. The latter is, therefore, a mere primitive condition, 
the formation of the root being a completion of the tooth development. 
As is almost always the case in nature, the intermediate condition between 
the two forms is next met with. Thus some teeth, as the molars of the 
horse and many rodents, are for a time rootless and have growing open 
pulps, which always indicate that in such states the teeth are continually 
elongating (growing). Naturally the edges of such teeth wear away from 
use. Ultimately, however, the pulps contract at the necks and distinct 
roots form, and the teeth cease to grow. In consequence of their greater 
firmness, the mammal's teeth are not used up so fast and do not require 
rapid replacement. There occurs only one change, in which the teeth, 
present at birth or developed soon after, are replaced by the second or 
permanent set (diphyodont mammals). In some instances (monophyo- 
dont mammals), there is no change, the first dentition being permanently 
retained (marsupials, perhaps toothed whales), or the first dentition is 
more or less rudimentary (edentates, many rodents, bats, seals, some 
insectivores) . Besides the two typical dentitions, traces of a third or 
even of a fourth may occur. A pre- temporary dentition of calcified germs, 
never functional, is seen in marsupials, but is rare in placental mammals. 
A dentition following the permanent one is outlined in many placentalia, 
and some of their teeth may exceptionally come into function. This 
condition is found sometimes in degenerates who are spoken of as having 
a third set of teeth. Hence, in man, it is a reversion to certain lower 
placental types. 

The medullary canals or pulps and development of mammalian teeth 
will be considered under separate chapters. It will be observed that in 
the phylogeny of each type of vertebrates, as well as in the vertebrate 
class as a whole, from fish to reptile and from bird to mammal, there is 
the widest range of evolution and degeneration, due to environment and 
adaptability und erthe law of economy of growth, or use and disuse, of 



A STUDY IN DEGENERATIVE EVOLUTION 331 

structures. This great variation in vertebrate classes, and from one class 
to the other in shape, attachment, number, development, position and 
structure, becomes less complicated as we advance in phylogeny. 

Summary 

Fish 

Degeneration of the teeth in fish, reptile, bird and mammal has been 
demonstrated. These changes have taken place for the benefit of the 
organism as a whole. 

Environment has caused greater and more numerous changes in the 
teeth than in any other structure of the body. Most of the changes are 
reversions, or arrests in phylogeny, to forms in some other class or in lower 
vertebrates. 

We have seen that dermal teeth and true teeth are identical structures 
which, in consequence of different positions and consequent difference in 
function, have developed differently. 

Sharks' teeth are nothing more than highly developed spines upon 
the skin. They are imbedded in tough mucous membrane and never 
acquire bony connection. 

Attachment. Teeth are attached to the mucous membrane by fibrous 
tissue, by bone attachment, by complete ankylosis, in grooves and in 
sockets. 

Number. Some fish are edentulous, namely the sturgeon, pipe fish 
and sea horse; others have horny plates. There is traceable in the various 
fish species every gradation in the multiplication of teeth. 

In all fish the teeth are shed and renewed throughout life. The teeth, 
therefore, are not permanent. 

Reptiles 

Reptile's teeth are nearly always conical, never branching into cusps 
at the tooth base. Those of the carnivora are sharp and thin, while those 
of the herbivora are blunt. 

Attachment. The most common attachment of the teeth of reptiles 
is ankylosis; some, however, are in grooves, prominences, slight depressions, 
or sockets. 

Number. Toads are edentulous. Tortoises and turtles have no 
teeth but horny plates. Marsh has discovered several species of Ptero- 
dactyls wholly without teeth. The jaws, which are more like those of 
birds than of reptiles, show no trace of teeth. 



332 DEVELOPMENTAL PATHOLOGY 

The adult Hatteria (lizard-like reptile) actually masticate upon the 
jawbone, the teeth having been worn away in early life. 

In some reptiles, there are as few as sixteen teeth in the upper and 
fourteen in the lower jaw. 

Medullary Canals. The medullary canals are all large. 

Mammals 

There are two types of dentition, — homeodont teeth, of one kind and 
shape, as in sloths, armadillos, dolphins, etc.; the other heterdont, the 
great majority of teeth being of different types, as in the dog and man. 

In the second division of mammalia, there is only one set of teeth, 
while in other mammalia, there are two sets. The dolphins, sloths and 
some armadillos have only a single set of teeth. 

In mammals, teeth are specialized and limited to localities, always, 
however, in the alveolar border. The monotremes have no true teeth. 
The young duck-bill has three flattened saucer-like teeth in each half of 
the jaw. These are shed and horny plates take their places. (A degener- 
ation.) The echidna is toothless. It has horny plates. 

There are only two teeth in the upper jaw of the adult narwhal. These 
cuspid teeth lie horizontally across the upper jaw. In the female, they 
are arrested in development and are perfectly concealed within the bone 
of the jaw, so that this sex is practically toothless. In the male, the right 
tooth remains concealed and abortive, showing the law of arrest of develop- 
ment and the law of compensation. The left is immensely developed, 
attaining a length equal to more than half the length of the animal. 

The whalebone whales have rudimentary teeth developed very early 
in life. They early disappear in the upper jaw and their places are taken 
up by the baleen (whalebone). 

The whalebone plates and the vascular ridge and papilla which form 
it, are comparable to the strong ridge upon the plates of certain herbivora. 

The teeth of the manatees are composed of two incisors, above and 
below, which are rudimentary and buried under horny plates which occupy 
the front of the mouth. There are forty-four molars, which are not, 
however, all in place at one time. The anterior ones are shed before the 
posterior one comes into place. 

In the dugong a single tooth makes its appearance before the incisive 
tusk. Scientists are undecided whether it is a rudimentary incisor or a 
milk tooth. In either case, it is a degenerative organ. The animal has 
two tusks, the greater part of which is imbedded in the alveolus. 

In the female the tusks do not project beyond the gum; the pulp 
cavities are closed. These abortive teeth are excellent examples of rudi- 



A STUDY IN DEGENERATIVE EVOLUTION 333 

mentary teeth, and are removed by absorption. They are clothed with 
dense horny plates. They are functionless. The dugong has five molars 
in each side consisting of dentine and cement only. 

In the ungulata, the teeth vary according to the habits of the animal. 
The dental formula in some of the earlier animals consists of three incisors 
in each jaw, one cuspid, four premolars, and three molars, making forty- 
four in all. Note that this type has six incisors, like some of the carnivora. 
In other ungulata; they are either degenerate or are entirely missing, as in 
sheep, cows, oxen, antelope, all the solid-horned ruminants (deer) also 
have this degeneration. Not a few of the group are without canines on 
the upper jaw. 

The upper canines, when present, are, with the notable exception of 
Maschus, Elaphodus, Cervulus and Hydropotes, small and laterally com- 
pressed rudimentary teeth. The roots are small and much reduced. 

The rodentia have no canine teeth. The incisors are large, curved 
teeth with persistent pulps. The molars have closed roots and do not 
elongate. 

The insectivora have some molars with the W-pattern, while others 
have the V-pattern. 

The carnivora are animals known by the name of "beasts of prey,'* 
such as cats, wolves, dogs, bears, weasels and allied animals. There is 
another type adapted to aquatic life, with limbs modified into swimming 
organs, as represented by seals and walrus. Some of this class do not live 
entirely upon flesh, therefore their teeth must be modified. Some of 
these are more herbivorous than carnivorous. Such changes would also 
change the alimentary canal. 

The carnivora possess, as a rule, three kinds of teeth; namely, incisors, 
canines and molars. These vary in number and shape according to the 
nature and food of the animal. Some molars are long and sharp, others 
short and broad. 

The quadrumana monkeys are the highest mammals next to man. 
From a purely anatomic point of view, the orang, the gorilla and the 
chimpanzee are in the same genera. 

In some of the lowest species (Galeopithecus, flying lemurs) there are 
thirty-four teeth, namely ten incisors, four canines and twenty molars. 
They have two incisors less above than below. The molars are studded 
with points, like the insectivora. The lower incisors are deeply notched 
on the cutting edge like the lemurs. 

The true monkeys are divided into the old and new world monkeys 
The new world monkeys are divided into marmosets, with thirty- two teeth, 
and the Cebidae, which have thirty-six. There are three premolars on 
each side. The old world monkeys have thirty-two, like man. 



334 DEVELOPMENTAL PATHOLOGY 

The Shapes of the teeth depend upon their position in the jaw and 
the special functions they are to perform. In fish, reptiles and toothed 
birds, the teeth are nearly all cone-shaped or cuspids. As we ascend the 
scale, the higher vertebrates (mammals) possess a variety of teeth. 

In the evolution of the higher vertebrates, the cuspid teeth are degen- 
erate in the female narwhal. They remain imbedded in the jaw; in the 
male, the law of economy of growth is well demonstrated in the right 
cuspid, which is imbedded in the jaw, while the left is unusually long, being 
fully one-half the length of the body of the animal. In the higher verte- 
brates, — the ungulata, the ruminants, the rodents and insectivora, — they 
are entirely wanting; they are again rudimentary in the mare, while in the 
stallion, they are well developed; occasionally mares have four canines, 
again only two in the lower jaw, all of which are imperfectly formed, 
showing an attempt on the part of nature to restore the teeth to their 
normal position; in the carnivora, they are again well developed and are a 
characteristic feature in these animals. 



Chapter XXVI 

THE PHYLOGENY AND ONTOGENY OF 
TOOTH DEVELOPMENT 

THE phylogeny and ontogeny of tooth development are so closely 
related, there being only slight modifications in the different groups 
of vertebrates, that they will be briefly considered under one head. 
The tooth germs are situated a little distance below the surface; 
those for placoid scales a little higher than those for true teeth. Each 
germ is composed of two parts; the enamel germ and the dentine germ. 
If we divide the mucous membrane, or skin, into two parts at the basement 
membrane, the upper part, or layer, of epithelium is the part from which 




Figure 252 
First appearance of tooth development (Frey). From a porcine embryo, d, mass of epithe- 
lium, — the "dental ridge," "maxillary rampart;" b, younger layer of epithelium; c, 
deepest layer — the columnar or prismatic stratum; e, enamel organ. 

the enamel germ is derived and that below the basement membrane, the 
deeper parts of the mucous membrane, is the part from which the dentine 
germ is formed. 

The enamel organ in its early stage, is formed independently of the 
dentine germ. The same is true of the dentine germ. It develops in a 
true mucosa, and is composed of nerves, arteries and veins, sometimes 
being called a dentine papilla. The two germs develop about the same 
time. If there be any priority, perhaps the enamel organ has a little the 
start. 

The first sign in tooth development consists in an enlarging of the 
epithelium over the germ (Fig. 252, d). Under this swelling there is a 
dipping down of the epithelium into the deeper tissues. This band of 
epithelial tissue extends around the surface of the structure where the teeth 
are to grow and which will eventually become the jaw bone. At different 
intervals a further development of the epithelial cells and a more highly 
organized mass of cells occurs. This mass of cells becomes the enamel 
organ. There are as many organs formed as there are teeth in each jaw. 

335 



336 



DEVELOPMENTAL PATHOLOGY 



Underneath each enamel organ, there is a specialization of tissue in the 
true mucous membrane which eventually forms the dentine papillae 
(Fig. 253). The dentine papillae now become organized and take the 
shape of the tooth which is to be formed at that particular locality. The 




Figure 253 
A simple papillae of the mucous membrane (Kolliker). Manifold vessels and epithelium 
from the gums of an infant. Shows principally the cells of the epidermis. Magnified 
250 diameters. 



enamel papilla, or organ, now grows downward or upward to meet the 
dentine papillae. When they come in contact, the enamel organ moulds 
itself about the dentine papillae or bulb (Fig. 254) to form the enamel 
cap. The enamel organs, while forming the enamel caps for the milk 
teeth, do not remain inactive, but send out a corresponding number of 
connective tissue papillae, the origin of the enamel organ for the future 
permanent teeth (Fig. 255, h). These new enamel organs are not situated 
on a plane with the tooth band of the temporary teeth, but are located, 
as described by Rose, in the upper jaw from above backward and from 
below forward; in the lower jaw from below backward and from above 
forward. By this arrangement, the temporary teeth germs lie nearer 
the periphery of the maxillary surface allowing the tooth band to expand 
without interfering with the development of the permanent teeth. As 
the enamel and dentine germs begin to calicify, there is a connective- 
tissue envelope which encloses the entire structure in a sac (Fig. 256). 
The inner part of the sac, which lies directly upon the true tooth structure, 
is made up of loose connective tissue with numerous blood vessels, while 
the outer surface is composed of dense connective tissue. The formation 
of this sac causes the epithelial cord to become severed from the enamel 



A STUDY IN DEGENERATIVE EVOLUTION 



337 




Figure 254 
Section through the incisive portion of the lower jaw of an ovine embryo, measuring 82 milli- 
meters (3| inches) in length (Legros and Magitot). D, oral epithelium; C, lowest 
layer of cells in the stratum malpighii; F, epithelial cord; K, bourgeon of the secondary 
cord; /, follicular wall; H, dental bulb. Magnified 260 diameters. 




Figure 255 
Section of upper jaw of kitten at birth (Tomes), a, oral epithelium; b, bone of jaw; c, neck of 
enamel organ; d, dentine papilla; e, enamel-cells; /, stellate reticulum; h, tooth germ 
of the permanent tooth, the enamel organ of which is derived from the neck of its pre- 
decessor. 



338 DEVELOPMENTAL PATHOLOGY 

organ. While the enamel and dentine germs are sojourned in this enclosed 
sac, the former develops the enamel and the latter the dentine in the 
crown. 

How well this is accomplished will depend upon the nervous system 
of the individual. If the nervous system be stable and nutrition normal, 
the enamel organ and dentine bulb will develop normal and produce 
healthy structures. If, on the other hand, the nervous system be unstable, 
owing to disease in parent or child, then the deposition of lime salts will 
become irregular, and pits, furrows and mal-formations will occur. It 
is possible that the depth of degeneracy may be so great that the enamel 
organ or the dentine bulb or even both will not develop, in which case the 
•enamel organ will develop the crown of the tooth without the root, as is 
frequently seen in degenerates and is an arrest in phylogeny at the stage of 
those vertebrates which possess only crowns of teeth. Again, the enamel 
organ may not form. The dental papillae will develop the dentine and 
the root will be perfectly formed. These roots will erupt into their normal 
position, but no crowns will present. Many illustrations are on record 
in which such conditions exist, an arrest in ontogeny. We frequently 
find in the mouths of children with an unstable nervous system, teeth 
with imperfectly formed enamel; its character is not unlike horn. Lime 
salts are wanting. Here again may be traced the law of arrest in phylo- 
geny corresponding to the horny plates and teeth of the lower vertebrate 
type. Occasionally, the germs of the teeth become faulty in development 
and remain in sacs in the jaw. Again, we have an arrest in phylogeny 
simulating the lower vertebrates. 

Occasionally the jaws at puberty will be edentulous; neither first nor 
second set are present in such persons, there is an arrest at those fish and 
reptile stages in which no teeth are present. 

Not infrequently a number of tooth germs will not form and only a 
part of the dental formula will erupt in the mouth as noted in Fig. 275. 
Here we have an arrest in phylogeny at fish and reptile stages. 

The germs of the second teeth should be located directly at the apical 
end of the roots of the temporary teeth, as in some reptiles and extinct 
birds. It is intended that these germs shall be so situated as to absorb 
the temporary roots while the second teeth are erupting. This, however, 
does not always take place. When the germs of the second teeth are 
located at the side of the roots, they represent an arrest in phylogeny at 
the stage of the fish and reptile whose teeth are continuous and develop 
at the sides of the previously developed teeth. 

After the enamel organ has formed, the epithelial cord is absorbed a 
second time. At this period the connection of the epithelial cord with the 
mucous membrane of the mouth, its source of nourishment, should be 



A STUDY IN DEGENERATIVE EVOLUTION 339 

severed or atrophied, since there is a fixed law that continued tooth develop- 
ment, as observed in the lower vertebrates, does not exist in the higher. 
The epithelial cord, if continuous with the oral epithelium, may still bud 
and develop new teeth called supernumerary teeth. These supernumerary 
buddings may produce one or any number of additional teeth. They 
may be connected with either the temporary or permanent set, and may 
be located in any part of the jaws. Odontomes of different varieties, 
conditions, and shapes, are also developed at this period, in the jaws of 
children possessing unstable nervous system. Buddings or debris of the 
cord are found in the lower mammalia, such as the horse, cow, ox, sheep, 




Figure 256 
Section through the incisive region of the lower jaw of human fetus, measuring 38 centimeters 
(153^ inches) (Legros and Magitot) . b, bony formation; d, oral epithelium; g, enamel 
organ; H, dental bulb; I, cord of the permanent follicle; K, debris of the follicular wall 
of the primitive follicle and from its cord; K, epithelial globule; L, enamel organ of the 
permanent tooth. Magnified 80 diameters. 

swine, rabbits, guinea pigs, as well as in man. It is no doubt an arrest 
in phylogeny at fish and reptile stages when more than thirty-two teeth 
are found. If the epithelial cells remaining in the alveolar process are 
merely debris, of which large quantities may be found (Figs. 256 k and 
257 k) in nearly all vertebrates, normal enamel organs cannot be formed 
for want of proper nourishment. 

It is not uncommon to find extra enamel organs and dental papillae 
forming lateral incisors in both temporary and permanent teeth, an arrest 
in phylogeny at the carnivora stage. 



340 



DEVELOPMENTAL PATHOLOGY 



Extra or supernumerary teeth owing to persistent enamel organs 
develop in the lower mammalia as well as in man. They may take the 
shape of the tooth adjoining, but in a majority of cases they are cone- 




Figube 257 
Section of lower jaw of bovine embryo showing the completed dental follicle and the surround- 
ing tissues (Legros and Magitot). a, Meckel's cartilage; b, traces of ossification; c, 
lowest layer of epithelial cells; d, oral epithelium; F, ameloblastic layer; F, (lower) 
external layer of the enamel organ — a continuation of the layer of ameloblasts; g, stellate 
reticulum of the enamel organ; H, bulb; I, follicular wall; K, buddings from the cord. 
Magnified 80 diameters. 

shaped, and are again an arrest in phylogeny corresponding to the primi- 
tive cone-tooth. 

Summary 



The tooth germ consists of two parts — the enamel germ, derived from 
the upper layer and the dentine germ, derived from the deeper part of the 
mucosa. 

The enamel papilla grows upward or downward to meet the dentine 
papilla, and meeting, moulds itself around the latter, and as they calcify 
a connective tissue sac encloses the whole, the enamel and dentine of the 



A STUDY IN DEGENERATIVE EVOLUTION 341 

crown being there developed. At this stage the epithelial cord is severed 
from the enamel organ. 

Under an unstable nervous system or hereditary defects, either organ 
may fail of development, producing a crown without a root or a root with- 
out a crown (arrest in ontogeny). The enamel may resemble horn or 
the teeth remain undeveloped in a sac in the jaw (arrests in phylogeny). 

The germs of the second teeth, instead of being at the apical end of 
the first teeth, may be located at the sides, developing new teeth in that 
position — an arrest in phylogeny at the fish and reptiles stage. 

The epithelial cord, (the medium of nutriment), instead of being 
severed at the proper juncture, sometimes persists and gives rise to super- 
numerary teeth — an arrest in phylogeny. These often occur in the lower 
mammals, and usually assume the form of the primitive cone-shaped 
teeth — a further arrest in phylogeny. 



Chapter XXVII 
THE ONTOGENY OF THE HUMAN TEETH 

HAVING studied the phylogeny and ontogeny of the teeth in a 
general way, we are now in a position to study the specific phylo- 
geny and ontogeny of the human teeth. 

It has been shown that the highest perfection of the tooth, from a 
pathologic standpoint, consists in the cone-shape crown and root, situated 
some distance apart in the jaw, as observed in crocodiles, toothed birds 
and the lower mammalia. Single roots and single crowns prevailed in 
phylogeny up to the mammalian class, when the greatest struggle for 
existence between organs took place. As the vertebrates advanced in 
evolution, the great diversity of environment, such as habits, methods of 
obtaining food, mating and feeding their young, caused numerous changes 
in shape, location and number of the teeth. 

The evolution of this primitive tooth to the bicuspid and molar has 
been explained by two theories — the concrescence and the differentiation. 
The first, advanced by Magitot in 1877, was later advocated by Schwalbe, 
Carl Rose and Kurkenthal. The last was offered by Osborn and Cope. 

The Concrescence Theory is bringing together several isolated 
teeth and forming bicuspids and molars. A number of conical teeth in 
line as they lie in the jaw of the shark represent primitive dentition. In 
the course of time a number of these teeth would become clustered together 
in such manner as to form the four cusps of a human molar, each one of 
the shark-tooth points taking the place of one of the cusps of the mammal- 
ian tooth — in other words, by a concrescence four teeth would be brought 
into one so as to constitute the four cusps of the molar crown. Vertically 
succeeding teeth might also be grouped. Now what evidence is there in 
favor of this theory and what is there against it? First, there is this, that 
all primitive types of fish and reptiles from which mammalians have de- 
scended, and many existing mammals, as we have noted, have a large 
number of isolated teeth of a conical form; second, we find that by a shorten- 
ing of the jaw the dental fold or embryonic fold, from which each of the 
numerous tooth caps is budded off in the course of development, may be 
supposed to have been brought together in such manner that cusps which 
were originally stretched out in line would be brought together so as to 
form groups of a variable number of cusps, according to the more or less 
complex pattern of the crown. 

The Differentiation Theory is the addition of cusps to the conical 
tooth. Going back over ten millions of years in the Triassic we find the 
mammalia, or the first animals which we can recognize as mammalia, 

342 



A STUDY IN DEGENERATIVE EVOLUTION 



343 



possessing conical, round, reptilian or dolphin-like teeth. There are also 
some aberrant types which possess complex or multituberculate teeth. 

"These teeth begin to show the first traces of cusp addition. In 
Plate A, Figures 1 and 2, the teeth of the dromatherium of the coal beds 
of North Carolina occur on the sides of the main cone cusps or rudimentary 




Plate A 
Evolution of human tooth (Osborn). Different stages through which the tooth passes to» 

form bicuspids and molars. 

little cusps. On either side of the main cone are two small cusps. In the 
same deposit occurs another animal represented by a single tooth (Plate 
A, Figure 3) in which these cusps are slightly larger. These cusps have 
obviously been added to the side of teeth and are now growing. In teeth 
of the Jurassic period, found in large numbers both in America and in 
England, but still of very minute size, are observed these same three 
cusps. These cusps have now taken two different positions; in one case 
they have the arrangement presented in Fig. 258. The middle cusp is 
relatively lower and the lateral cusps are relatively higher, in fact, these 



344 



DEVELOPMENTAL PATHOLOGY 



cones are almost equal in size. These teeth are termed triconodont, as 
having three nearly equal cones. But associated with this is the spala- 
cotherium, the teeth of which are represented in Plate A, Figure 4. Here 
is illustrated the transformation of a tooth with three cusps in line into a 




Figure 258 
Lower fossil jaw and teeth of animal of Jurassic period (Osborn) . 

a line. 



Shows roots and cusps on 



tooth with three cusps forming a triangle. Here the primitive cusp is the 
apex of a triangle of which the two lateral cusps are the base. This tooth, 
in this single genus, is the key of comparison of the teeth of all mammalia, 
and by this can be determined that part of a human molar which corre- 
sponds with a conical reptilian tooth. This is the triangle stage, and the 
next is a development of a heel or spur upon this triangle (see the amphith- 
erium, Plate A, Figure 5). The opossum still distinctly preserves the 
ancient triangle. Look at it in profile, inside or top view, and see that 
the anterior part of the tooth is unmodified. This triangle is traceable 
through a number of intermediate types. 

*'In Miacia (Plate A, Figure 6), a primitive carnivore, is a high tri- 
angle and a heel; looked at from above (Plate A, Figure 6a) the heel is 
seen to have spread out so that it is as broad as the triangle. The three 
molars of this animal illustrate a most important principle, namely, that 
the anterior triangle portion of the crown has been simply leveled down 
to the posterior portion. These three teeth form a series of intermediate 
steps between a most ancient molar and the modern molar of the human 
type, and the second tooth is half way between the first and the third. 
The second molar seen from above, has exactly the same cusps as the first, 
so it is not difficult to recognize that each cusp has been directly derived 
from its fellow. The third tooth of the series (Plate A, Fig. 7) has lost one 
of the cusps — of the triangle. It is now a tooth in which only half the 
triangle is left on the anterior side and with a very long heel. That tooth 



A STUDY IN DEGENERATIVE EVOLUTION 345 

has exactly the same pattern as the human lower molar (Plate A, Fig. 8), 
the only difference being that the heel is somewhat more prolonged. These 
teeth belong to one of the oldest fossil monkeys, anaptomorphus. Human 
lower molars not infrequently have five cusps instead of four, and the 
fifth always appears in the middle of the heel or between the posterior 
lingual and the posterior buccal. This occurs in monkeys and other 
animals, but no record exists of the ancient anterior lingual reappearing. 
The human lower molar, with its low, quadrituberculate crown, has hence 
evolved by addition of cusps and by gradual modeling from a high-crowned, 
simple-pointed tooth. 

"Carl Rose has contributed considerably to our knowledge of the 
evolution of the teeth. He says, 'I find no mention in literature of the 
development of the teeth of the chameleonidae, nor of any other acrodont 
reptile. As the chameleon possesses multituberculate molars in the 
posterior portion of its jaws, therefore the development of the teeth in this 
animal must be doubly interesting, especially with regard to the origin of 
the molars generally.' 

"Fig. 259 shows the teeth of the upper jaw of the chameleon five times 
magnified. The anterior teeth are unituberculate, the posterior one 




Figure 259 

Upper jaw of a chameleon (Rose). Shows three classes of teeth conate, bi-conodont and 

tri-conodont. Magnified five times. 

bi- or trituberculate. All teeth are fused to the edge of the maxilla. There 
is no shedding of the teeth in the chameleon, nor could I prove it to take 
place in hatteria; but still there is, especially in the upper jaw, behind 
the functional teeth, a well developed dental or reserve ridge. On its 
posterior end there takes place, throughout life, a continuous new forma- 
tion of teeth. Accordingly older animals have always a larger number of 
teeth than young ones. Although I examined microscopically, with a 
lens, a number of heads of the chameleon, and microscopically six different 
series of sectionized jaws, I never succeeded in finding any indications of 
reserve teeth." 



346 



DEVELOPMENTAL PATHOLOGY 



To alientists, biologists, criminal anthropologists, and sociologists 
the human jaw and teeth are of peculiar interest, since their study estab- 
lishes many points in phylogeny and ontogeny not clearly determinable 
in other structures. Their study enables the observer, without much 
difficulty, to determine inherited and acquired stigmata. For this purpose 
the teeth should be studied from the first evidence of their development 
until they are all in place, which occurs normally, in most cases, by the 
twenty-second year. 

Enamel of the teeth, as has been shown, is formed from the epiblast, 
dentine, cementum, and pulp (except as to nerve tissue) from the meso- 
blast. The enamel organs of the first set are formed during the seventh 
week of fetal life, the dentine bulb during the ninth week. At this period 
the tooth obtains its shape and size and calcification begins at its periphery. 
This models the enamel cap, which fits over the dentine like a glove. 
When imperfections in hand or fingers exist, these deformities are distinctly 
observed upon the glove. In precisely the same manner are observed 
the different shapes and sizes of the incisors, cuspids and molars. Cal- 
cification of the teeth begins at the seventeenth week of fetal life. Fig. 
260 shows the progress of calcification and development of the temporary 

22 months alter liirth 

18 „ 




18th 
\7th „ 



Figure 260 
Diagram of eruption and calcification of temporary teeth (Pierce). 



set of teeth. Examination will show that every defect in nutrition from 
conception to birth, due to an unstable nervous system, has been registered 
upon the teeth. The state of the constitution and the locality registers 
the date of such defects. Thus, if the tooth be larger or smaller than at 
the present stage of evolution, it is either an arrest in phylogeny or onto- 
geny. If, on the other hand, there be defect at any part on the crowns 
of the teeth, and the contour be imperfect the date of malnutrition can be 
easily determined by consulting this chart. More or less than the normal 
number of teeth, abnormally placed, demonstrate the existence of the 
depth of degeneracy to which the fetus has been subjected, since the 



A STUDY IN DEGENERATIVE EVOLUTION 



347 




2 Q 0» 



348 DEVELOPMENTAL PATHOLOGY 

germs must have been deposited at the periods mentioned. No absolute 
rule can be laid down as to the date of the eruption of the teeth. The 
temporary teeth erupt nearly as follows: 

After Birth. Time of Erup 

Lower central incisors 7 months 1 to 10 weeks 

Upper central incisors 9 months 4 to 6 weeks 

Upper and lower laterals 12 months 4 to 6 weeks 

First molars 14 months 1 to 2 months 

Cuspids 18 months 2 to 3 months 

Second molars 26 months 3 to 5 months 

The enamel organs and dentine bulb for the permanent teeth form 
just before birth (Fig. 261) in like manner with the temporary set. They 
form just above the temporary set on the upper and below on the lower 
jaw. The permanent molars begin to calcify at the twenty-fifth week of 
fetal life. The permanent incisors do not calcify until a year after birth. 
Any deviation in size or contour of the permanent teeth from the normal 
must hence be due to defect in nutrition in the dentine bulb between the 
fifteenth and twenty-fifth week of fetal life. Any deviation in calcification 
(except the cusps of the first permanent molars) must occur after birth. 
At the third year, twenty-four teeth are fairly well calcified. At the fifth 
year the second permanent molars and at the eighth year the third molars 
or wisdom teeth begin to calcify. 

The following table gives the approximate age of eruption of perma- 
nent teeth: 

First permanent molars 6 years 

Upper and lower central incisors 7 years 

Upper and lower laterals 8 years 

First biscuspids 9 years 

Second bicuspids 10 years 

Cuspids 11 years 

Second permanent molars 12 years 

Third permanent molars 17 to 24 years 

Man at his present stage of evolution has twenty teeth in his tempor- 
ary and thirty-two in his permanent set. Any deviation in number is 
the result of embryonic change, occurring between the sixth and fifteenth 
week for the temporary teeth, between the fifteenth week and birth for 
the permanent. The germs of teeth which erupt late in life and are (prop- 
erly) called third sets, of necessity appear ere birth, and are completely 
formed at the beginning of the second year, although they remain protected 
in the jaw until late in life. 



A STUDY IN DEGENERATIVE EVOLUTION 349 

More than twenty teeth in the temporary or thirty-two in the per- 
manent set is, therefore, an arrest in phylogeny. 

From a maxillary and dental standpoint, man reached his highest 
development when his well-developed jaws held twenty temporary and 
thirty-two permanent teeth. Decrease in the numbers is an arrest in 
ontogeny, although it marks advance in man's evolution as a complete 
being. Marsh points out that in the New Mexican lower eocene occur a 
few representatives of the lowest primates, such as the lemuravus and 
limnotherium, each the type of a distinct family. The lemuravus, most 
nearly allied to the lemurs, is the most generalized primate yet found. 
It had forty-two teeth in continuous series above and below. The lim- 
notherium, while related to the lemurs, had some affinities with the Ameri- 




Figure 262 
Supernumerary permanent incisors (original) . 

can marmosets. Dr. A. H. Thompson, in discussing the "missing teeth" 
of man, remarks that these researches of Marsh suggested and subsequent 
studies aided the solution of the problem of the origin of the extra teeth 
(known as supernumeraries) that sometimes occur in man. They are, 
however, excellent illustrations of atavism and demonstrate that man 
during his evolution from the lowest primate has lost twelve teeth. " These 




Figure 263 
Supernumerary temporary lateral incisors (original). Some of the carnivora have four lateral 

incisors in the upper jaw. 



350 



DEVELOPMENTAL PATHOLOGY 



supernumerary teeth assume two forms — either they resemble the adjoin- 
ing teeth or are cone-shaped. 

Supernumerary Teeth Resembling the Normal. While they 
rarely are exactly counterparts, every tooth can be and is duplicated, as 
the following illustrations show. Fig. 262 illustrates fairly well-formed 
duplicate central incisors, the normal incisors being outside the dental 
arch. They are crowded laterally by the large roots of the supernumerary 
incisors. Fig. 263 shows an extra right lateral in a temporary set in the 
upper jaw; Fig. 264 an extra right lateral in the permanent set. Fig. 




Figure 264 
Supernumerary permanent lateral incisors (original). 

265 illustrates duplicate incisors, cuspids, bicuspids and molars. These 
are located in the vault of the mouth. They are normal duplicates of the 
regular teeth. Their location, however, is of interest since it is an arrest 
in phylogeny at the fish stage simulating the Port Jackson shark (Fig. 266). 
Fig. 267 shows supernumerary third molars, also an arrest in phylogeny 




Figure 265 

Supernumerary permanent centrals, cuspids, bicuspids and molars (original). Simulating 

the jaws and teeth of the Port Jackson shark. 



A STUDY IN DEGENERATIVE EVOLUTION 



351 



at a primitive stage. The teeth, which fail to approximate their normal 
neighbors, assume the cone-shape of the primitive tooth. 

Supernumerary Teeth — Cone-Shafed. The fact that the cone- 
shaped tooth, as a rule, is perfect in construction, is found everywhere in 




Figure 266 
Jaws and teeth of Port Jackson shark (original) . 

the jaw, but especially in the anterior and posterior part of the mouth, 
is of much value in outlining tooth and jaw evolution, especially from 
degeneracy aspects. The upper jaw, being an integral part of the skull, 
and fixed, is of necessity influenced by brain and skull growth, hence 
degeneracy is more detectable in it than in the lower. 




Figure 267 
Supernumerary permanent third molars (original). 



352 



DEVELOPMENTAL PATHOLOGY 



The evolution of the jaw is towards shortening in both directions. 
This shortening will continue so long as the jaw must be adjusted to a 
varying environment. The jaw of man having originally contained more 
than thirty-two teeth, lack of adjustment to environment brings about 
arrest in ontogeny of the jaw and atavism of the teeth due to the shorten- 
ing. While this may coincide with general advances of the individual, 
it indicates that he is not yet adjusted to his new environment. The 
shortening of the upper jaw causes supernumerary cone-shaped teeth to 
erupt in mass at the extreme ends of the jaw. Fig. 268 shows three super- 
numerary teeth; a cone-shaped tooth between the central and the lateral, 




Figure 268 
Cone-shaped permanent supernumerary teeth (original) . 



and cuspids out of position. The left permanent lateral is at the median 
line, another cone-shaped tooth remains in the vault, while the super- 
numerary left lateral is in place. As many as eight are at times to be 
observed in the anterior vault. Posteriorly these teeth are most often 
noticed in connection with third molars, usually on a line with other teeth, 
posterior to the last molar. Fig. 269 shows cone-shaped molars in the 




Figure 269 
Cone-shaped supernumerary third molars (original) . 



A STUDY IN DEGENERATIVE EVOLUTION 



353 



posterior part but outside of the dental arch. Supernumerary cone-shaped 
teeth however, are not confined to these localities but may be observed 
at any point in the dental arch, Fig. 270. This illustration shows the 




Figure 270 
Teeth in their evolution (Smale and Colyer). The teeth show the process of evolution as 

illustrated in Plate A. 



depth to which degeneracy may attack the teeth, only two molar teeth 
can be said to be normal and these are situated considerably forward of 
their normal position. The cone-shaped teeth are typical arrests in phylo- 
geny, while the last two molars are fine illustrations of the arrests in phylo- 
geny at the primitive carnivora stage (miacis, Plate A, Fig. 6). The 
primitive cone-shaped tooth is rarely observed in the lower jaw. In 
forty years' practice I have not seen a case. The mobility of the lower 
jaw prevents that maladjustment to environment so commonly present 
in the upper. 




Figure 271 
Permanent third molar missing (original). 



354 



DEVELOPMENTAL PATHOLOGY 



The continual shortening in both directions of the jaw causes the 
third molars frequently so to wedge in between the angle of the jaw and 
the second molar that eruption, if possible, is difficult. The third molar 
is often absent in the Caucasian races. In forty-six per cent of six hundred 
and seventy patients, it was missing. Frequently its development is 
abortive. This tooth in the struggle for existence seems destined to dis- 
appear. It is more often absent from the upper than the lower jaw. 




Figure 272 
Both third molars missing (original). 



When absent or badly developed the jaw is smaller, and frequently teeth 
irregularities, nasal stenosis, nasal bone and mucous membrane hypertro- 
phy, adenoids, and eye disorders coexist. Fig. 271 shows absence of the 
left third molar with irregularities of that side of the arch, — a marked 
arrest in ontogeny of only one side of the dental arch. In Fig. 272, both 




Figure 273 
Permanent laterals missing (original). 



A STUDY IN DEGENERATIVE EVOLUTION 355 

third molars are missing, an arrest in ontogeny in both dental arches. 
Anteriorly the lateral incisors are most often wanting. Fourteen per cent 
of laterals were wanting in six hundred and seventy patients. 

In the progress of evolution, some of the carnivora possess two lateral 
incisors upon each side of the jaw. In man, however, only one lateral 
incisor remains, and this tooth seems also destined to disappear. In 
Fig. 273 both lateral incisors are absent. Not infrequently does it occur 
that centrals, cuspids, bicuspids and even molars are absent. Even their 
germs are not detectable. Fig. 274 illustrates a cast showing three super- 




Figure 274 

Cone-shaped teeth (American System of Dentistry). Decay taking place rapidly in the 

cone-shaped molars, owing to want of proper material to fill the spaces. 

numeraries in the anterior part of the mouth and two cone-shaped molars, 
— arrests in phylogeny as to shape of teeth and arrests in ontogeny as to 
numbers. 

The absence of teeth indicates lack of development of germs due to 
defective maternal nutrition. 

Cone-Shaped Teeth. Crescent-shaped bitubercular, tritubercular, 
as well as all deformed teeth tend to the cone-shape. The malformation 
of these teeth results from precongenital trophic change in dentine develop- 
ment. It consists in dwarfing and notching the cutting and grinding 
edges of the second set of teeth, a familiar example of which is seen in the 
so-called "Hutchinson teeth," usually referred to a syphilitic etiology. 
Hutchinson's position has, however, been more strongly stated than his 
own words warrant, since he admits that in at least one-tenth the cases 
luetic etiology could be excluded. 

Lues only plays the part of a diathetic state, profoundly affecting the 
maternal constitution at the time of dentine development. While these 
teeth may be due to secondary result of lues, they do not always demon- 
strate luetic heredity, since any constitutional disease, especially those 



356 



DEVELOPMENTAL PATHOLOGY 



in which dermal structures are involved will produce the same condition- 
The character of the malformation depends upon the severity of the disease- 
In Fig. 275 are seen the teeth of an individual affected with constitu- 
tional disease, and by referring to Fig. 261 we shall see that the defective 




Figure 275 
So-called syphilitic teeth (American System of Dentistry). Ridges in teeth at different 
periods of calcification due to constitutional diseases preventing proper material from 
being deposited. These teeth tend to conate. 

lines represent the respective ages of two and a half, four and five years. 
The degree of pitting depends, as a rule, upon the severity of the con- 
stitutional disorder. In the case just cited, however, although nutrition 
was but slightly disordered, each tooth shows a tendency to conate. The 
cutting edges of the incisors also take serrated forms of the teeth of the 
anteater and flying lemurs. Not infrequently are cavities extended 
completely through the tooth. The cusps of the permanent first molars 
calcifying at the first year are usually attacked also and arrested in develop- 




A 



Figure 276 
Arrest of development of the upper jaw and bicuspid teeth (original). The bicuspids are 
malformed with a tendency to conate. A V-shaped dental arch is formed. The right 
lateral is missing. 



A STUDY IN DEGENERATIVE EVOLUTION 357 

ment, producing the cone shape. These data, together with dates of 
eruption of the temporary and permanent teeth, furnish an absolute 
basis for calculation as to excessive or arrested development. The cutting 
edges of the teeth take the serrated forms and are an arrest in phylogeny 
at the lemurian stage. Fig. 276 shows a very degenerate jaw with cone- 
shaped malformed bicuspids, — an arrest in phylogeny. The right lateral 
is missing, the cuspids are erupting in the vault, and the dental arch is 
assuming a V-shape. The jaw as a whole shows marked arrest in develop- 
ment. Fig. 277 shows "Hutchinson" teeth. Were the first molars 
visible they would present marked contraction of the outer surface with 




Figure 277 
So-called "Hutchinson" teeth (American System of Dentistry). Owing to constitutional 
disease proper material not being furnished, the teeth conate; the center becomes 
notched and the enamel is badly formed. 

a malformed center. Referring again to Fig. 261, we observe that 
trophic changes affected the system at the age of birth. Such diseases as 
lues and the eruptive fevers which involve the skin have a most deleterious 
effect upon the enamel of the teeth since those structures are derived from 
the epithelium. The outer surface exhibits a tendency to take the cone 
shape. 

Figs. 278, 279, 280, 281 exhibit malformations and assume the cone- 
shape. The center is drawn together but there is not enough material 
(lime salts) to fill in and produce a perfect crown. The formation is not 
unlike the cranium in which gaps occur, Fig. 34. All four of these illustra- 
tions clearly demonstrate the concrescence theory of bicuspid and molar 
evolution. The coincidence in form between "Hutchinson" and mal- 




Figures 278-279 
Shows differentiation theory with tendency to conate (Smale and Colyer) . 



358 



DEVELOPMENTAL PATHOLOGY 



formed teeth and those of the chameleon demonstrates that tropho-neurotic 
change produces atavistic teeth. Fig. 282 illustrates the tendency of 
human bicuspids (when there is no antagonism) to rotate one fourth round, 




Figure 280 
Shows differentiation theory with tendency to conate (Smale and Colyer). 

thus again demonstrating the atavistic tendency toward the teeth of the 
chameleon. All the teeth in this illustration, including the incisors, cuspids, 
bicuspids and molars are arrests in phylogeny since they all tend to conate, 
demonstrating a marked unstable nervous system in both parent and 




Figure 281 
Shows differentiation theory with tendency to conate (Smale and Colyer). The center of 
this tooth has decayed from want of properly formed enamel and dentine in the center 
of the tooth under the law of economy of growth. 

child. Fig. 283 exhibits extreme arrest in phylogeny at the sauropsidian 
stage. All teeth anterior to the molars are cone-shaped. The third 
molars are missing and would probably never erupt. This illustration 




Figure 282 
Lower jaw and rotation of bicuspids (original). 

nicely demonstrates a more marked depth of degeneracy than the previous 
figure. In Fig. 284 appears more marked arrest in phylogeny at the 



A STUDY IN DEGENERATIVE EVOLUTION 359 

sauropsidian stage. The upper and lower anterior teeth are cone-shaped 
and the superior first bicuspid exhibits a tendency thereto. The right 
superior second bicuspid, second and third molars, the right inferior first 
and second bicuspids, second and third molars are missing. The same 




Figure 283 
Lower jaw showing conate teeth (Smale and Colyer). 

condition probably exists on the left side. The space in the upper jaw is 
due to the insufficient width of the teeth, and is also an arrest in phylogeny, 
a normal condition in fish and reptile. 

Tooth Degeneration and the Differentiation Theory. In 
degenerate jaws, the influence of the factors of the differentiation theory 



Figure 284 
Upper and lower jaws showing conate teeth (Smale and Colyer) . 

are also demonstrated. Every tooth in the jaw at one point or another 
may display rudimentary cusps. On the incisors they are always to be 
found on the lingual surface. 

Fig. 285 illustrates the centrals with two rudimentary cusps, the 
laterals with one and the cuspids with one. These are arrests in phylogeny 
observed in Plate A. A lingual cusp on the incisor is seen in the horse 
(Fig. 286) which is normal. I have observed two instances, in my prac- 
tice, where a lingual cusp developed on the inner surface of the incisors, 
(Fig. 287). This is an arrest in phylogeny as observed in the previous 
figure. 

Fig. 288 represents cusps upon the lingual surfaces of the molars. 
The cuspids, which have since developed, are not unlike the lower bicuspids 
with a rudimentary lingual cusp. 

Thompson remarks there is a gradation from central incisors towards 
the bicuspids in evolution. This grading of form is not observed from 
cuspid to bicuspid evolution in man. But we must remember that the 



360 



DEVELOPMENTAL PATHOLOGY 



cuspid presents a cingulum on the lingual face that inclines it toward the 
bicuspid forms in lower mammals, like the mole, and that the first pre- 




Figure 285 
Upper jaw showing cusps on basilar ridge of cuspid teeth (original). 

molar or bicuspid is then more caniniform, the inner tubercle being much 
reduced. This inner tubercle is variable and erratic as to its position. 
It appears as far front, as has been shown, as the centrals and is often 




Figure 286 
Section of the incisor of horse showing lingual cusp at basilar ridge (Owen) . 



A STUDY IN DEGENERATIVE EVOLUTION 361 

present on the lingual face of the laterals of man. The lingual tubercle 
is very constant on the first bicuspid of man and is as well developed as the 
buccal. But in some lower forms, as in the lemurs, it is quite deficient. 




Figure 287 
Cast showing cusp on human central at basilar ridge (original) . 

It attains the highest development only in the anthropoids and man. 
Considering these stages of development, the grading from the cuspid to 
the bicuspid forms was more gradual in the earlier species than in the 
later, where the individual teeth have taken on special development. 




Figure 288 
Cast showing supernumerary cusps on first permanent molars (original). 



362 DEVELOPMENTAL PATHOLOGY 

In the skull of a degenerate girl who died from tuberculosis at thirteen 
years of age, among other stigmata is a cusp on the external surface of a 
right inferior cuspid. This is a decidedly strong point in favor of the 
differentiation theory. Another strong point in favor of this theory is 
shown in Fig. 289, where every tooth is present and a most remarkable 
display of cusps occurs. The cusps upon the cutting and grinding edges 




Figure 289 
Cast showing evolution of the teeth as seen in Plate A demonstrating the differentiation 

theory (Smale and Colyer). 

are not obliterated. Commencing with the left superior central incisor 
three cusps are present with a rudimentary palatine cusp. The laterals 
also show three cusps, while the cuspid has two very distinct — arrests in 
phylogeny at the lemurian stage. The illustration as a whole nicely 
demonstrates the entire evolution of the molar from the single cone tooth 
as shown in Plate A. The first and second bicuspids have tubercular 
cusps, they being in line. The buccal cusps upon the molars two to three 
are still in position. The palatine cusps have not developed. The same 
is the case upon the opposite except that the cuspid has cusps that have 
fused together, leaving a small projection upon the mesial side and a 
rudimentary palatine cusp. The cusp upon the third molar is lost. In 
the cuspids, bicuspids and molars, the prominent cusps denote an arrest 
in phylogeny as shown by Osborn at the early stage of tooth development. 
In another case (Fig. 270) , the primitive cone teeth are seen trying to shape 
themselves into incisors. The lateral incisors, cuspids, and bicuspids are 
still cone-shaped. The first permanent molar is fairly formed, while the 
second molars are still in a primitive condition. 



A STUDY IN DEGENERATIVE EVOLUTION 363 

Tooth Degeneration and Concrescent Theory. There is abun- 
dant evidence to show that degenerate teeth unite in twos, threes, fours, 
and fives, as indicated in the concrescent theory. These single cone- 
shaped teeth grow together and form bicuspids and molars. The germs 




Figure 290 
Union of two central incisors demonstrating the concrescence theory (Smale and Colyer). 

of any two normal teeth may intermingle and unite; not only are the 
crowns found united with separate roots, but crowns and roots are united 
throughout. 

Figs. 290 and 291 show two superior central and lateral incisors joined 
together throughout the entire length of crown and root; Fig. 292, two 




Figure 291 
Union of two superior central incisors demonstrating the concrescence theory (Smale and 

Colyer). 

lower incisors are united throughout; Fig. 293 shows a cuspid with two 
roots; this is an arrest in phylogeny simulating the lower mammals such 
as some lemurs, moles and hedge-hogs. Dr. George T. Carpenter, of 




Figure 292 
Union of two inferior incisors demonstrating the concrescence theory (Smale and Colyer). 

Chicago, had a right superior second bicuspid with three well-formed 
roots; Fig. 294 illustrates two bicuspids united at the crowns trying to 
produce molars; Fig. 295 shows two molars perfectly united; Fig. 296 



364 DEVELOPMENTAL PATHOLOGY 

illustrates central and lateral incisors of the permanent set perfectly united ; 
Fig. 297 shows two molars united; Fig. 298, a molar and supernumerary 
united, the supernumerary taking the cone-shape with deformed center. 
Fig. 299 shows three malformed teeth, each conated and completely united. 




Figure 293 
Union of two roots to form a cuspid tooth demonstrating the concrescence theory (Smale and 

Colyer) . 

Both these groups of single teeth united together beautifully demonstrates 
how roots, crowns and cusps are developed. 

It is not uncommon to find three molars united as for instance the 
second, third, and supernumerary molar. Dr. C. V. Rosser, Atlanta, 




Figure 294 
Union of two bicuspids demonstrating the concrescence theory (Smale and Colyer). 

Georgia, has two small molars and a supernumerary cuspid perfectly 
united from crown to root, and these three further united to the roots of a 
well-formed molar. Thus we see the concrescence theory is fully estab- 
lished.* 




Figure 295 
Union of two molars demonstrating the concrescence theory (Smale and Colyer). 

*Since degeneracies of the differentiation theory and the concrescent theory are com- 
monly found among the human race, it is possible that from the argument used in this 
work both theories may be partially or wholly correct. 



A STUDY IN DEGENERATIVE EVOLUTION 



365 



A condition of a molar tooth occasionally observed in America, but 
more often in England, Scotland and Ireland, is that in which the crown 
is flattened from side to side (Fig. 300), and the roots nearly or quite on a 
line. Instead of being normal as in Fig. 301, they stand as in Fig. 302, 
arrest in phylogeny simulating those in Fig. 258. These teeth are generally 
observed in jaws of arrested development. The third or last molar, be it 




Figure 296 
Union of the inferior incisors demonstrating the concrescence theory (Smale and Colyer). 

second or first, is usually affected. Sometimes more than one molar is 
thus involved as well as the bicuspids. This occurs in jaws where the 
depth of degeneracy is most marked. 




Figure 297 
Union of two molars demonstrating the concrescence theory (Smale and Colyer) . 

Dr. S. H. Guilford was the first to call attention to this particular 
anomaly in 1887. He says, "Among the anomalies of tooth structure or 
formation, this one is quite rare. The crowns of this character are flattened 




Figure 298 

Three single teeth joined together throughout forming a molar tooth with cusps demonstrating 

the concrescence theory (Smale and Colyer). 



366 DEVELOPMENTAL PATHOLOGY 

in an anteroposterior direction, so that their diameter transversely of the 
jaw is by far the greater one. The fissures or sulci, instead of presenting 
the usual form, are distorted and sigmoid in shape, corresponding with 
the long diameter, while the cusps resolve themselves into narrow ridges 




Figure 299 
Three single teeth joined together throughout forming a molar tooth with cusps demonstrat- 
ing the concrescence theory (Smale and Colyer). 

somewhat after the manner of the molars of the ruminantia. The third 
molars of the superior arch are the ones usually affected because of their 
degenerative nature. 




Figure 300 
Malformed crown of third molar tooth (Dental Review) . An arrest in phylogeny simulating 

the carnivora tooth. 

William Booth Pearsoll, of Dublin, Ireland, also called attention to 
this abnormality at the 1888 meeting of the Royal College of Surgeons, 
Ireland. The question arose in connection with extraction, since there 
was difficulty in seizing the tooth with the forceps because of the shape 
of the crown and roots. These teeth are usually found in degenerate 
jaws. Like most dental abnormalities observed in degenerate jaws, these 
teeth are phylogenetic, reverting in crown and roots to the original "tri- 
conodont" type (carnivora) with cusps and roots in line. The roots are 
sometimes separated, containing two or three, or there may be only one 
flattened upon the sides. The pulp chamber shows the root canals also 
in line. 

Children Born with Teeth. Children are sometimes born with 
incisor teeth. This is an arrest in phylogeny at the lower mammalian 



A STUDY IN DEGENERATIVE EVOLUTION 



367 



(marsupial) stage. A foal is born with two rudimentary central incisors 
in each jaw. 

Serrated Teeth. The incisors of both temporary and permanent 
teeth, when developed, have fine serrated edges, Fig. 303. The greater 



A I 



Figure 301 Figure 302 

Diagram showing normal position of roots Phylogenic position of roots of molar tooth 
of molar tooth (Dental Review) . (Dental Review) . Simulating the position 

of the primitive cone tooth. 

the depth of degeneracy, the more marked are these serrations, Fig. 289. 
This is an arrest in phylogeny at the insectivora stage, but more particularly 
at the lemurian, Fig. 304. This is the most marked example. These 



□ 



Figure 303 
Cast showing serrated teeth (original) . The incisors upper and lower, while erupting usually 

present these indentations. 

serrated teeth serve to scrape the ants from the tongue. The serrations 
are soon worn away in the human. Six incisors are sometimes developed 
in the human, an arrest in phylogeny at the carnivora stage. Occasionally 
the lateral incisors are not developed (Fig. 303) — an arrest in ontogeny. 
Non-Eruption of Cuspid Teeth. It is not uncommon to find the 
cuspids unerupted and lying in the vault of the maxillary bone, Fig. 305. 



368 



DEVELOPMENTAL PATHOLOGY 



This is an arrest at the narwhal stage, in which the cuspids are located 
near the center of the upper jaw, Fig. 306. In the male, there is an arrest 
of development of the right cuspid, while the left is excessively developed 
under the law of economy of growth. The female has both cuspids arrested 
in development, and both are imbedded in the jaw. 

Excessively Developed Cuspid Teeth. Not infrequently, the 
cuspid teeth are excessively developed and are prominent, with long roots, 




Figure 304 
Upper incisors of the Flying Lemur (Owen). These teeth are deeply notched. 

an arrest in phylogeny at the carnivora stage. The saddle arch is a recapit- 
ulation of the development of the teeth in the carnivora which, owing to 
the small jaw, with want of harmony in the size of the teeth, could not 




Figure 305 
Cast of upper jaw showing imbedded cuspid (Salter). 

period. 



An arrest in phylogeny at the narwhal 



The 



possibly take any other form, owing to the order of tooth eruption, 
prominence of the cuspid teeth give character to the human face. 

Long Crown Teeth. Teeth with long crowns and very short roots 
are sometimes seen in children having an unstable nervous system, Fig. 
307. This is an arrest in phylogeny and is found in the hysodont (having 



A STUDY IN DEGENERATIVE EVOLUTION 



369 



long crowns), Fig. 308. The teeth of the early horse are shown in the 
smaller illustration, while that of the modern horse is a tooth with a long 
crown. Change in evironment, more particularly in the food, has brought 




Figure 306 
Upper jaw of narwhal (Owen). The left cuspid is arrested in development and lies imbedded 
in the jaw. The right cuspid is excessively developed and is more than half the length 
of the animal. This illustration only shows that part of the tooth imbedded in the jaw. 
In the female, both cuspid teeth are arrested in the jaw. 

about this change. The long crown provides for a much longer period of 
mastication. Nature has made wise provision for erosion. Erosion in 




Figure 307 
Elongated human molar (American System of Dentistry). 

modern horse. 



Simulates the molar tooth of the 



370 



DEVELOPMENTAL PATHOLOGY 



human teeth, therefore, is an arrest in phylogenetic development, a phylo- 
genetic return to those teeth in the lower vertebrates having persistent 
pulps. The erosion in the human, therefore, is atavistic. The fact that 
the pulps in human teeth contract in root development is a degeneration. 
Undeveloped and Rootless Teeth. Occasionally, teeth are seen 
with short undeveloped roots and again without roots. This is an arrest 



;■■ ■'■<■: '•■ "' ■?■ ■? 



-wm 





Figure 308 
Elongated tooth'of modern horse (Tomes). The small illustration is that of a tooth with 

cusps of the primitive horse. 

in phylogeny which takes place at the period in which teeth are present 
with persistent pulps and without roots. 

) |Teeth in large well developed jaws with large bell-shaped crowns and 
dense, hard, well developed enamel are an arrest in phylogeny. 




Figure 309 
Cast showing tooth roots without crowns (American System of Dentistry) . 



Crownless Teeth. Roots of teeth are occasionally seen in the 
jaws of defective children without crowns, Fig. 309. This arrest in ontog- 



A STUDY IN DEGENERATIVE EVOLUTION 371 

eny occurs at the very commencement of tooth development on account 
of a defective enamel organ or the enamel organ may not be present. 

Teeth sometimes develop without enamel, or the enamel is in cir- 
cumscribed areas. Sometimes the enamel is not normally calcified. These 
are arrests in development at the lower vertebrate type and are due to 
defect in the enamel organ. Each structure is an evolution in development 
in each class until we reach the mammal, when all are nearly alike. 

Development and Eruption of Permanent Teeth. The perma- 
nent teeth should develop and erupt under the temporary, as in the higher 
reptiles and toothed birds, for the purpose of assisting in absorption of 
the roots of the temporary teeth. When, however, they develop at the 
sides, it is a phylogenetic arrest at the sauropsidian stage, where there is 
persistent eruption of the teeth. Teeth with more than one root are a 
mammalian feature. 

Degenerate Teeth tend toward the cone-shape, a reversion in 
phylogeny to fish, reptile and toothed bird type. Occasionally, in degen- 
erate jaws and teeth, especially later in life, ankylosis occurs. This is a 
tendency to the phylogenic ankylosis of lower vertebrate teeth. Teeth 
in each class, fish, reptiles, toothed birds and mammals, recapitulate 
themselves in most particulars and are therefore arrests in phylogeny. 

Occasionally, man's second set of teeth do not develop. More 
commonly, however, one or more temporary teeth remain in the jaw. 
This is a phylogenic arrest at those vertebrate types which possess only one 
set of teeth. 

The Molar Teeth of the anthropoid apes grow larger from before 
backward; in the Australian (the lowest human race) they are all of one 
size, while in modern races, in our present state of evolution, they diminish 
in size from the first molar back showing the gradual degeneration of the 
human teeth. Occasionally the second or third or both human molars 
are as large or even larger than the first. Again, an arrest in phylogeny. 

Occasionally a fourth molar is found. This is an arrest in phylogeny 
at the primitive race stage. 

When a human tooth is larger than the normal, it has usually developed 
at the expense of an adjoining tooth Which is smaller under the law of 
economy of growth. 

Spreading Roots. Teeth with roots spread widely apart are an 
arrest at the simian or higher ape stage (Fig. 310). 

Supernumerary Teeth. We have shown that supernumerary teeth 
are an arrest in phylogeny at those vertebrates which have more than 
thirty-two teeth. Tomes has shown that supernumerary teeth are found 
in the anthropoid ape. It would be strange if they were not found in 
other mammalian species since in the higher mammals, the teeth are more 



372 DEVELOPMENTAL PATHOLOGY 

uniform in number. That man should be the only mammal with super- 
numerary teeth would not be in harmony with natural fixed laws. In 
all mammals, therefore, but more especially in man, since the fact has been 
demonstrated, supernumerary teeth are an arrest in phylogeny at the 
sauropsidian stage. This is further borne out by the fact that the rudi- 
mentary enamel organs, called by early writers "debris" (Fig. 256 and 
257), are to be observed in the alveolar process of carnivora, herbivora 
and human. 

Sets of Teeth. No mammal has normally more than two sets of 
teeth, twenty in the temporary and thirty-two in the permanent. When 




Figure 310 

Third molar tooth of pithecanthropus erectus (Dubois), (a) side view showing short crown 

with distended roots; (b) showing surface of crown. 

more than these are found, they are called supernumerary teeth and are 
an arrest in phylogeny. When less than this number is present, it is an 
arrest in ontogeny. Man, therefore, has reached his highest physical 
development when his jaws contain thirty-two well developed teeth. 

There are, no doubt, many other degenerations of the teeth due to 
arrests in phylogeny and ontogeny but enough have been demonstrated to 
show the significance of this law. 

Summary 

The highest perfection in tooth development is the cone or cuspid 
tooth. This tooth is to be found in all classes of vertebrates. Single 
crowns and roots prevail up to the mammalian, when crowns change to 
meet the environment and more than one root is found. 

The evolution of the primitive (single crown and root) tooth to the 
bicuspid and molar type (a purely mammalian change) has been explained 
by two theories: the concrescence (grown together) theory and the differ- 
entiated (changing the shape) theory. Both these theories are illustrated 
in the phylogeny and ontogeny of tooth development. 

The calcification of the teeth takes place at nearly stated intervals, 
as outlined by Pierce. Man at his highest physical development has 



A STUDY IN DEGENERATIVE EVOLUTION 373 

twenty teeth in the temporary and thirty-two in the permanent set. When 
more, it is an arrest in phylogeny; when less, it is an arrest in ontogeny. 
When there are more than thirty-two teeth in the permanent set, they are 
called supernumerary and take the shape of the tooth adjoining, or the 
phylogenic cone-shape. 

As man adjusts himself to the new environment, the jaws shorten 
in both directions. This calls for fewer number of teeth. The shortening 
of the jaws and the dropping of the teeth, however, do not take place 
uniformly, the result of which is that the third molars become impacted in 
the jaw. Again, the long diameter of the jaws is smaller than the long 
diameter of the teeth, as a result of which irregularities occur. Because 
of the shortening of the jaws, the teeth at either end, the third molars and 
the incisors, become degenerate, imbedded in the jaw, or are wanting 
altogether. In six hundred and seventy patients, forty-six per cent of 
third molars did not develop; while in the same number of patients, four- 
teen per cent of laterals did not develop. When we consider that in many 
of the lower mammals, four laterals are present in each jaw, it shows 
rapid arrest in the anterior jaws of the human. 

In disease, especially of a marked constitutional nature and in which 
the skin is involved, such as lues and the eruptive fevers of children, the 
effect upon the enamel organ, derived from the epithelium, is most severe. 
The more severe the disease, the more indelible is the stamp of degeneracy 
upon the teeth. 

It makes no difference what teeth are involved, incisors, cuspids, 
bicuspids or molars, the tendency of degeneracy in phylogeny is toward 
the cone-shaped tooth. 

Tubercles or cusps may be seen on any of the teeth in the mouths of 
degenerate children, showing a tendency to the differentiation theory. 
In degenerate jaws, crowns and roots are found fused together, illustrating 
the concrescence theory. 

Molars and bicuspids are found flattened upon the sides, and the roots 
are nearly or quite in rows, an arrest in phylogeny at the carnivora stage. 

The incisors have serrations upon the cutting edges at the time of their 
eruption, an arrest at the lemurian stage. 

Cusps sometimes develop upon the basilar ridges of the incisors, an 
arrest in phylogeny at the horse stage. Teeth are sometimes developed 
with short roots, again without roots, an arrest in phylogeny at the persist- 
ent pulp stage, where the teeth do not have roots. Roots of teeth some- 
times develop without crowns, an arrest in ontogeny. 

When the second teeth develop to one side of the temporary, it is an 
arrest in phylogeny at the stage where there are continuous teeth, as in 
the shark, some snakes, etc. 



374 DEVELOPMENTAL PATHOLOGY 

Man's second set sometimes do not develop. It is not uncommon 
to find some of the temporary teeth in the jaw throughout life, an arrest 
in phylogeny at those vertebrates possessing only one set of teeth. 

When the second and third molars are as large or larger than the 
first, it is an arrest at the Australian stage, the lowest human type. Oc- 
casionally a fourth molar is seen, an arrest at the primitive race stage. 
Teeth with roots spread wide apart is an arrest at the higher ape stage. 
Supernumerary teeth are found in the anthropoid apes. It would be 
strange if they were not present in all mammals, a reversion to the fish type. 



Chapter XXVIII 
THE DENTAL PULP 

THERE are three forms of pulp degeneration; namely, phylogenetic, 
ontogenetic and pathologic. The first two may be considered 
physiologic. 

Phylogenetic Degeneration of the Pulp is a gradual evolutionary 
diminution in its structure from the original placoid scale and horny plate, 
through the various stages of fish, reptile, extinct toothed birds and lower 
mammals to the ape and man where the apical end of the root is nearly 
closed. The phylogeny in pulp degeneration, like that of root degenera- 
tion, is complete in each class above the fish type. 

Ontogenetic Degeneration of the Pulp is a gradual diminution 
in the structure from the dentine bulb (placoid scale and horny plate stage) 
at the beginning of the formation of dentine to the period at which the 
root of the tooth has completely formed. 

Pathologic Degeneration of the Pulp consists of diseases affect- 
ing the pulp tissue after it has become senile. 

The Phylogeny of the Dental Pulp is not unlike the phylogeny 
of the teeth. The pulp of the tooth was originally the dental papilla 
developed beneath the basement membrane and is, therefore, dermal in 
its origin. It is unlike the enamel organ in that it contains nerves, arteries 
and veins, which the enamel organ does not. The dental papilla, in its 
development, shapes itself according to the shape of the structure which 
it eventually produces. This process varies from broad placoid scales and 
horny plates to the closed apical end of the tooth root. 

In the teeth of fish, reptiles and extinct birds, and lower mammals, 
the pulps are as large as the base of the tooth, hence the teeth obtain 
complete nourishment. In some mammals (the tusks of elephants, the 
incisors of the rodentia, etc.), the teeth continue to grow and are kept 
alive by persistent pulps also as large as the tooth roots. Such tusks and 
teeth do not possess roots. 

In other vertebrates, the pulps contract at the tooth neck and gradually 
grow smaller until at the apical end only a nerve, artery and vein enter. 
In each class of vertebrates, fish, reptile, extinct bird and mammal, there 
is a repetition of the evolution of the pulp from horny plates with surface 
pulps, through the persistent pulps and teeth with partially developed 
roots, to the nearly closed apical end where only a nerve, artery and vein 
enter the tooth root. The same order exists in the mammalian series. 

In the lowest mammal, the ornithorhyncus, there are horny plates 
in the anterior part of the mouth and horny plates with teeth in the center 

375 



376 



DEVELOPMENTAL PATHOLOGY 



of the posterior part, the roots are soft and not well formed. In the advance 
toward the higher mammals, the pulps contract at the neck and in the 
anthropoid apes and man are nearly closed. 

The Ontogeny of the Dental Pulp is a repetition of its phylogeny, 
not only in each class of fish, reptile, extinct bird and mammal, but also 
from the lowest to the highest vertebrate. 

Human tooth pulps are formed from the deeper layers of the mucous 
membrane. Their method of dentine formation was described in Chapter 
XXVI, "The Phylogeny and Ontogeny of Tooth Development." It was 
there shown that the ontogeny was not unlike the phylogeny. The pulps, 




Figure 311 
Diagram showing the phylogeny of the roots of the teeth (original). No. 1, tusk of elephant, 
with peristent pulp and without roots; No. 2, the crown of a cuspid tooth with the 
enamel and dentine perfectly formed but the root has not yet commenced to develop. 
At the present stage this tooth resembles No. 1. No. 3, shows the development of the 
root and is not unlike roots of the rodent and all teeth with persistent pulps. No. 4, 
shows further progression of root development. No. 5, still further root formation. 
Arrests in phylogeny of the human tooth may take place at any one of these stages. 
No. 6, shows the fully developed human tooth. 



A STUDY IN DEGENERATIVE EVOLUTION 377 

in beginning to form dentine, resemble the persistent pulps of the elephant 's 
tusks, No. 1 compared with No. 2, Fig. 311. The pulps and their functions 
are the same. As soon as the dentine of the crown has formed, the pulp 
begins to contract, like those in single teeth of the lower vertebrates. 
The contraction and calcification continues as in Nos. 4, 5, 6 (Fig. 311), 
until the root has completely formed. Not infrequently in children with 
an unstable nervous system, arrest in phylogenetic development occurs 
at the fish, reptile or lower mammal stages, and the roots may fail to 
develop, as in Nos. 2, 3, 4, 5 (Fig. 311). 

When the pulp has completed root formation with only a nerve, 
artery and vein, nourishment has nearly ceased and the tooth, so far as 
disease (interstitial gingivitis) is concerned, is a foreign body. It does 
not grow, but remains a degenerate structure in the jaw. The pulp, after 
root formation, becomes senile and being more or less inactive is the best 
illustration of an end organ in the human body. It is, therefore a fit 
structure to hold poisons and foreign substances circulating in the blood, 
for after they once enter, they have no means of escape. 

The dentine of the tooth, being derived from the dentine bulb, depends 
upon it for normal development. In degenerate and neurotic children 
with unstable nervous systems, and those children who have inherited or 
acquired disease, the dentine bulb is apt to be abnormally developed. 
Again, the unstable nervous system which presides over pulp and dentine 
development may also produce abnormality in these structures. These 
abnormalities may be phylogenetic in character, such as the structures 
which compose the placoid scales, horny plates and the defective structure 
of the teeth of fish, reptile and lower mammals. Again, the dentine may 
become defective in its ontogenetic development. Under such pathologic 
conditions, defective teeth, with a want of tooth resistance to decay, are 
often seen. 

Lymphatic and Vasomotor Systems. 

Before discussing pathologic degeneration of the dental pulp, its 
lymphatic and vasomotor systems must first be studied. Without a 
knowledge of these structures, the student will be unable to understand 
pulp diseases. 

Lymphatics. The question of lymphatics in the dental pulp is still 
unsettled. Sudduth, Black and Boedecker are of opinion they do exist, 
while Tomes, Prieswerk, Miller and others hold the opposite. I have 
studied the dental pulp for many years to determine, if possible, a solution 
of this much discussed question. From the diseases observed in the pulp 
it would seem almost conclusive that lymphatics are not present, while 



378 



DEVELOPMENTAL PATHOLOGY 



on the other hand, Fig. 330 shows a healed abscess in a human pulp. 
Abscesses in persistent pulps are known to have healed; especially is this 
true in the pulps of elephants' tusks. While I have never been able to 
demonstrate lymphatics, oval spaces of different sizes and shapes occur 
in many pulps. In some instances they are perfectly round, but commonly 
flattened upon their sides without walls (Figs. 312 and 313). Their exact 
nature is uncertain. Researches have shown that septic material and 
micro-organisms have been carried from the pulp into the neck glands. 
Dr. Korner Halle, of Berlin, by an injection of Prussian blue into the pulp 




Figure 312 
Microscopic section of the human dental pulp showing so-called lymph spaces, cut longitudinal 

(original). X 143. 



tissue proved that the particles could find their way from the pulp into 
glands. He experimented upon dogs' teeth, exposing the pulp, painting 
it with Prussian blue and cementing the cavity. Two or three days after- 
wards the dogs were killed and the pulps of the teeth as well as the sub- 
maxillary glands examined with the microscope. Particles of Prussian 
blue were found throughout the pulp, to the apex of the root, and also in 
the lymph glands. This would be sufficient proof that if lymphatics are 
not present in the pulp, nature has provided a partial means for its care 



A STUDY IN DEGENERATIVE EVOLUTION 



379 



in disease. It is certain that pulps do repair themselves, lymphatics or 
no lymphatics. Miller mentions a case described by Gysi, and records 
three in his own practice, with illustrations, in which the human pulp, 
after being diseased, has thrown out secondary dentine and repaired tooth 
decay. The pulp was restored to health. Abscesses are constantly 
occurring in the pulp from infection and poisons circulating in the blood 
stream. These abscessed areas are later restored to health, as I have 
demonstrated in Fig. 330. 

The Vasomotor System. A study of the vasomotor system of the 
pulp is of interest. In no other structure of the human body is a study 




Figure 313 
Microscopic section of human dental pulp showing so-called lymph spaces, cut crosswise 
(original). These spaces are without walls. X 45. 



of the vasomotor nerves and nerve degeneration rewarded by such splendid 
results. Structures can here be obtained in apparently healthy persons 
which in other tissues of the body can only be had in disease. 

The nerve trunks, in passing through the jaw, are composed of nerve 
fibers gathered into bundles or funiculi, called the perineurium, and are 
held together by connective tissue. The connective tissue, in this instance, 
is called the epineurium. The cut ends, under the microscope, resemble 
the end of an ocean cable, the wires represented by the nerve fibers, and 
the rubber covering by the connective tissue sheaths. 

From this nerve trunk, smaller medullated nerve fibers are given off 



380 



DEVELOPMENTAL PATHOLOGY 



at the nodes of Ranvier, which pass up and into the apical foramina of the 
roots of the teeth. Sometimes there are two, three, ten or more nerve 
fibers entering the foramina. The number depends on the size of the 
apical opening. My researches have shown that in animals whose teeth 




Figure 314 
Microscopic section of dental pulp showing nerve trunk (original). Nerve fibers torn from 
main nerve trunk and entering the canal through the apical foramen. X 50. 

were in continuous eruption, the pulp was larger at the opening than in 
the pulp chamber. In man, the permanent teeth have small openings 
especially late in life. In the very nature of things, as man advances in 
age, but more especially in exostosis, the openings grow smaller. In a 
general way, motor, sensory and sympathetic nerves have been traced 
from their source to the roots of the upper and lower teeth. In no case 




Figure 315 

Microscopic section of dental pulp showing vasomotor system of nerve fibers (original). 

Nerve fibers encircling an artery showing terminals, X 50. 



A STUDY IN DEGENERATIVE EVOLUTION 



381 




Figure 316 
Microscopic section of dental pulp showing arteries and vasomotor system (original). Cross- 
ing of nerve fibers from one bundle to another. These extend along and around blood 
vessels, X 50. 



V 



: $\ 




iBE 



Figure 317 

Microscopic section of dental pulp showing arteries and vasomotor system (original) . Nerves 

around a cross cut artery. Y-shaped artery in center showing terminals. X 50. 



382 DEVELOPMENTAL PATHOLOGY 

(to my knowledge) has the character of the nerves of the pulp been demon- 
strated. 

In the preparation of the pulps to demonstrate nerve fibers and their 
diseases, special stains were necessary. These stains bring out the nerve 
tissue, leaving other tissues of the pulp very indistinct. 

The nerve fibers, after leaving the main trunk in the jaw, evidently 
enter the apical foramina in single nerve bundles. In many instances, 
these nerve bundles continue the entire length of the pulp without branch- 
ing. On the other hand, the branching sometimes begins after the trunk 
nerves have passed through the apical foramina. 

In Fig. 314 when the tooth was extracted, the pulp protruded from 
the end of the root, the opening being large. In this illustration, the 
nerve fibers are shown from the inferior dental nerve extending through 
the apical foramina in the root canal of the tooth. They seem to run in a 
bundle or funiculus, with the exception of one fiber, isolated at the root. 

Fig. 315 shows bundles of nerve fibers loosely arranged running in 
different directions. Between these bundles, may be seen many single 
nerve fibers running in all directions. In the center of the field is an 
artery, cut crosswise, with terminal fibers encircling it two-thirds around. 

Fig. 316 beautifully illustrates the vasomotor nerves in their relation 
to the blood vessels. The blood vessels and nerves run in the same direc- 
tion. In the center of the field may be seen four arteries. Nerve fibers 
are noticeably running the entire length between, but they cross and 
recross at different localities. Nerve fibers, in bundles and singly, cover 
the entire field. 

Fig. 317 shows bundles of fibers with many single fibers throughout 
the field. In the center may be seen an artery, cut lengthwise branching 
in two directions. The most interesting item of all, however, is an artery, 
cut crosswise, with vasomotor terminal nerves encircling it. 

Fig. 318 demonstrates the vasomotor system more thoroughly. In 
the center of the field may be seen nine arteries, cut lengthwise, and one 
cut crosswise. Bundles of nerve fibers run between the arteries and along 
the arterial walls. Nerve fibers are seen crossing and recrossing the 
arterial walls, sometimes in bundles and again in single terminal fibers. 
In the cross cut artery, a nerve fiber may be seen almost encircling it. 

Fig. 319 shows an enlarged artery, cut lengthwise, while just below 
it may be seen an artery running toward it at right angles. In this artery 
only the outer surface is seen. In both arterial coats, terminal nerve fibers 
are well shown. 

Fig. 320 shows the ends of the nerves cut crosswise. An artery may 
also be seen with a nerve encircling it. 

Fig. 321 illustrates the crown end of the pulp, with a bundle of nerve 



A STUDY IN DEGENERATIVE EVOLUTION 



383 




Figure 318 
Microscopic section of dental pulp showing arteries and vasomotor system (original). Five 
arteries with nerve fibers running lengthwise, also cross and long section of artery with 
nerve fiber around it. Thickening of arterial walls showing terminal nerve fibers. X 50. 




Figure 319 
Microscopic section of dental pulp showing arteries and vasomotor system (original) . Nerve 
extending along the arterial wall. At right angles may be seen the muscular coat of an 
artery filled with terminal nerve fibers. X 60. 



384 



DEVELOPMENTAL PATHOLOGY 



fibers which have extended intact the entire length of the pulp, distributing 
fibers throughout odontoblastic layer. 

Considering that the blood vessels and nerves pass through the pulp 
in a wavy direction and not in straight lines, the procuring of so many 
beautiful specimens showing so clearly and distinctly the vasomotor 
system is very fortunate. 

Pathologic Degeneration. Beginning with the proposition that 
phylogenetic and ontogenetic development of the pulp from the placoid 
scale to its present state in adult life is a physiologic degeneracy, it is not 
difficult to trace pathologic degeneracy, as I have already discussed its 
lymphatic and vasomotor systems. 

The causes which bring about diseases of the tooth pulp consist of 
changes in the blood stream. These changes are due to poisons circulating 



A 




Figure 320 
Microscopic section of dental pulp showing cross section of nerve fibers (original). Bundles 
of nerves in pulp showing vasomotor system. Crosscut section showing ends of nerve 
fibers also nerve encircling crosscut artery. X 25. 



in the blood. The poisons are the result of degenerative conditions occur- 
ring at or around the fourth period of stress, at the senile stage, or at the 
period of evolution. 

Not infrequently, the senile stage occurs prematurely in neurotics 
and degenerates. At this period, all excretory organs are weakened, 
resulting in faulty metabolism and autointoxication. Marked disturbances 



A STUDY IN DEGENERATIVE EVOLUTION 385 

take place in all the structures of the body, including the alveolar process 
(causing interstitial gingivitis) as well as the pulp. Morbid changes in 
the pulp, other than nerve end degeneration as already discussed, may be 
summed up as inflammation, abscess, nerve end degeneration, thrombosis, 
embolism, endarteritis obliterans, arterio-sclerosis, amyloid degeneration, 
hyaline, colloid, mucoid degeneration, pulp stones, fatty degeneration, 
neoplasm and fibroma. Some of these have been discussed by Arkovy. 
Tomes, Wedl, Smale and Colyer, Hopewell-Smith, Black, Boedecker. 
Andrews, Romer, Morgenstein, Caush, Latham and many others, and can 
be studied more at length in the original monograph. 

It is not my intention to study each morbid condition, but to show 
that the pulp is susceptible to them (individually and collectively) resulting 
in tooth degeneration. 




Figure 321 
Microscopic section of dental pulp showing distribution of nerves in odontoblastic layer 
(original). Bundles of nerves in the pulp showing the nervous system. These nerves 
extend to the odontoblastic layer. Small fibers running below and to the odontoblasts 
forming a nerve plexus. X 50. 

Pathologic degeneration of the dental pulp begins when it has ceased 
to form dentine and the apical end of the root is nearly closed. This 
structure, enclosed within bony walls, cannot expand and contract like 
other tissues when diseased, and poisons circulating in the blood give rise 
to many pathologic phenomena. 



386 DEVELOPMENTAL PATHOLOGY 

Inflammation. The phylogeny, ontogeny, anatomy and physiology 
of the pulp, from its transitory and end organ aspect, render it very sus- 
ceptible to inflammation. 

Owing to the peculiar shape and location of the pulp, the small capil- 
laries, and thin walls, the increase of blood pressure in the small capillaries 
and veins, due to irritation, is sufficient to cause rupture without the added 
influence of vascular changes, especially in cases of marked obstruction. 

If the outflow of venous blood in a given vascular area be totally inter- 
rupted, diapedesis of the red blood corpuscles from the involved capillaries 
and veins starts up as a result of the local increase in intravascular pressure. 

The exodus of blood corpuscles, through vascular degeneration, occurs 
particularly after mechanic, chemic and thermal lesions of the vessel walls ; 
certain poisons also affect the vessel walls with especial virulence. Claude 
Bernard's experiments show that dilations of the vessels follow paralysis 
of the local ganglia in their walls, while a disease like diabetes produces 
vasomotor neuroses upon end organs. 

Vasomotor constriction of the pulp causes pure arterial hyperemia. 
Arterial dilation and redness are produced by constitutional disease or 
constriction at the apical foramina. As a result of this dilation, the blood 
current meets with less resistance in the pulp chamber and a greater amount 
of blood flows into it. The pressure of the corresponding capillary rises, 
as the blood remains under greater pressure on account of the diminished 
peripheral arterial resistance. It is in this manner that the capillary and 
venous pulsation so frequently noticed in the teeth is brought about. 
There is no part of the body in which local hyperemia is so apt to occur 
as in the pulp, since constriction is always present. 

Active hyperemia produces swelling of the pulp tissue, which owing 
to its restricted space within the walls of the tooth, cannot expand and in 
the apparent absence of lymphatics, debris cannot escape. The serum of 
the blood transudes into the tissue, and, there being no collateral circula- 
tion, death of the pulp necessarily follows. 

Local anaemia or ischemia may result from lack of blood supply in 
the pulp, either from constriction, disease, thrombosis of the arteries or 
the nerves at the apical end of the root, due to disturbance of the vaso- 
motor system. 

Narrowing of the arteries increases the resistance of the current and 
the blood reaches the pulp capillaries under low pressure. This causes 
them to contract and their surface area is materially diminished. End or 
terminal arteries, like those in the pulp, supply a definite organ or portion 
of the body and they have little or no anastomosis. They are also found 
in the spleen, kidney and certain parts of the brain and retina and are 
characteristic of end organs. 



A STUDY IN DEGENERATIVE EVOLUTION 



387 



When local anaemia, resulting from constriction of a terminal artery, 
occurs, as at the end of a tooth root, or as a result of dilation due to the 
vasomotor system, death of structure or organ takes place by coagulation, 
stagnation, neurosis or thrombosis. 

When circulatory disturbances arise, stasis takes place. When, 
according to Hektoen, the capillary loses all its plasma, as in local anaemia, 
inflammation results from constriction due to the vasomotor system, 
thereby closing the apical end of the tooth root. Vasomotor disturbances, 
producing or accelerating inflammation, have often been demonstrated. 
It is enough to say that any disease or action of the vasomotor system 
upon terminal structures (like the pulp) apparently without lymphatics, 
constricted at the apical end and enclosed in bony walls, is very apt to 
produce or hasten inflammation. 




Figure 322 
Microscopic section of dental pulp showing arteries, nerves and foci of inflammation around 
arteries (original). In the center above and below may be seen nerve end degeneration. 
X50. 

Abscess. Inflammation and abscess may occur at any locality in 
the pulp. I have observed, as will be shown, an area of inflammation 
with abscess at the horn, at the center of the pulp, and also in the apical 
end. The inflammatory process may pass through all the stages, from 
pus infection to abscess, without pain to the patient. 



388 



DEVELOPMENTAL PATHOLOGY 



Tomes, Salter, Wedl and Harris all find that pulp inflammation may 
occur without exposure. 

Black (American System of Dentistry) takes the student through the 
different processes of inflammation, where there is exposure of the organ. 
The same process results in inflammation of the pulp, except that the cause 
is internal instead of external. Whether resolution takes place or not will 
depend largely upon the vasomotor system, and the size of the apical 
foramina to allow for circulation. 

Figure 322. In this section of the pulp from a molar there are in the 
crown some large cells (myeloid) and pulp stones, which, by much irritation, 









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Figure 323 
Microscopic section of dental pulp showing arteries, nerves and foci of inflammation around 
arteries (original). Similar to the previous figure. The inflammation and nerve end 
degeneration, however, are more marked. X 156. 



have caused inflammation on one side even to abscess formation, vessel 
dilation and a foci of red-cell infiltration. The other side is comparatively 
healthy, but has the round-celled infiltration showing in its very earliest 
condition. One, the smallest, just beneath the odontoblast layer, with 
well marked nerve fiber just beyond. A second, still further towards the 
center of the pulp on the other side of it, shows a large nerve trunk, even 
the internode being visible in the low power, and just above it an area of 



A STUDY IN DEGENERATIVE EVOLUTION 



389 



nerve degeneration. Still lower down a darkening area of inflammation 
is to be seen, showing a ruptured vessel, a large number of round-cells 
with a small vessel or capillary shaped as a Y branching across a continua- 
tion of the lower nerve trunk. Nerve degeneration in various stages is 
well marked. 

Figure 323 shows a similar condition to Figure 322. This area was 
just beneath a coronal abscess with necrosis. Cells were pushing into the 
connective tissue stroma and involving the arteries in some places. Just 
below one of the vessels cut nearlv to the endothelial coat is a circumscribed 




Figure 324 
Microscopic section of dental pulp showing round celled infiltration (original). 

an abscess will form. X 67. 



Eventually 



abscess, one of a series of multiplying abscesses which occur all through the 
specimen. The special nerve staining renders it a difficult matter to bring 
out all the cellular detail, but same can be well understood under the 
microscope. 

Figure 324 is a cross section of pulp with very early localized round- 
cell infiltration just beneath the odontoblasts. The pulp shows a slight 
increase in connective-tissue cells all through it. Numerous nerve trunks 
are scattered here and there both in cross and oblique sections. 

Figure 325 shows a further stage of Figure 324 with some cloudy 
swelling, coagulation and a slight central necrosis situated beneath and 



390 



DEVELOPMENTAL PATHOLOGY 



to one side of the odontoblasts. Fibrous tissue with interstitial pulpitis 
is well seen further under the abscess, with considerable fatty degeneration 
at one end. Figure 326 is a very advanced sequela of inflammation occur- 
ring near the coronal portion of the pulp. Above the part photographed 
the tissue has fallen out from necrosis. There is a well marked necrotic 
area with considerable round-cell infiltration. Some cells take the hema- 
toxylin stain very well, many of them, polynuclear leucocytes and others, 




Figure 325 
Microscopic section of dental pulp showing round celled infiltration further advanced 

nal). X 67. 



(origi- 



hardly take it at all. Some attempts at fibroid tissue formation can also 
be seen, forming a trabecular for the cells in places. There are also a few 
very small pulp stones. 

Figure 327 is even further advanced than Fig. 326. The whole of 
one horn is entirely inflamed and rapidly terminating in suppuration and 
necrosis. Many cells are in a state of parenchymatosis degeneration. 
Between strands of fibrous tissue, thickened and sclerosed nerve trunks, 
there are a very few small pulp stones around one end. On the further 
horn the odontoblasts are faintly outlined. In one spot there is a very 
small localized abscess, well marked round-cell infiltration; beneath, the 
pulp is nearly normal, only a slight increase in odontoblasts. Passing 



A STUDY IN DEGENERATIVE EVOLUTION 



391 



down towards C, another abscess and a liquefying area appears, and to the 
outer odontoblastic zone a sclerosed nerve in a hyaline fibroid tissue; the 
odontoblasts are no longer to be seen, their nutriment basement layer has 
fallen away at the lower part; a few again appear towards the cervical 
pulp as normal odontoblasts, but under same and deeper in the tissue is 
some fatty degeneration with a fibroid root portion of the pulp. 

Figure 328. The interest of this photomicrograph lies in the fact 
that the abscess is situated midway of the curved part between the bifurca- 
tion of the roots. The whole pulp is filled with a greatly increased cell 




Figure 326 
Microscopic section of dental pulp showing active inflammation and breaking down of tissue 

(original). X 131. 



infiltration, especially in Weil's layer beneath the odontoblasts, the latter 
being granular in appearance. All the blood vessels are swollen and filled 
with a hyalin coagulation. A granular amorphous debris is seen every- 
where through the basic substance of the pulp. 

Figure 329 illustrates the extreme apical end of the pulp. One horn 
of the crown end is entirely destroyed by an abscess; the other horn is 
healthy. The nerve fibers are well stained. Passing down is a narrow 
area, slowly changing to a condition of atrophy. Below this the tissue 



392 



DEVELOPMENTAL PATHOLOGY 



seems to be in a healthy condition. As we pass down toward the apex 
several small areas of round-cell infiltration may be seen, forming abscesses 
similar to Figure 322. The extreme apical end is shown in the picture, 
poorly-stained areas (cloudy swelling), some small fatty areas, trunks of 
degenerating nerve fibers, — a suppurative area among the fiber and blood 
vessels with necrosis at the tip of the pulp apex. An artery cut across 
with thickened walls may also be seen at the left of the picture. 

I shall here call attention to this beautiful illustration, Figure 330. 
At A, diseased pulp in which is seen a circumscribed area of acute inflamma- 
tion about to liquefy and form an abscess; C, a fully formed abscess, and 
B, the cicatricial tissue of an old abscess, showing conclusively that restora- 




Figure 327 
Microscopic section of dental pulp showing active inflammation and breaking down of tissue 

further advanced (original). X 29. 



tion of a diseased pulp is possible. Speaking of want of lymphatics in the 
pulp Miller says, "It is for this reason that an abscess or center of inflam- 
mation the size of a pinhead in the pulp of a human tooth may cause ex- 
cruciating pain, while its presence on the surface of the body might escape 
notice altogether." This, however, is not often the case. I have shown 
that in neurasthenia, hysteria, degeneracy and many diseases the peripheral 
nerves lose their sensation and hence little or no pain is experienced. 
Lymphatics are not connected with sensation except as to relief of pressure, 



A STUDY IN DEGENERATIVE EVOLUTION 



393 



but nerve disorder readily interferes with transmission of pressure symp- 
toms, necessary to constitute pain. 

Nerve End Degeneration. For the purpose of studying this 
subject, teeth were collected, cracked open, and the pulps placed in differ- 
ent fluids for cutting, staining and mounting. Many methods and stains 
were used. Some of the stains that were successful on nerve tissue in 
other parts of the body were of little 01 no value on pulp tissue, for its 




Figure 328 

Microscopic section of dental pulp showing active inflammation and breaking down of tissue, 

formation of abscess (original). X 55. 

unstable and degenerate nature makes the structure rarely twice alike. 
Care and attention are required to obtain good results. 

Fig. 331 (partly schematic) shows Wallerian degeneration of nerve 
fibers after section. Thoma. 1, normal nerve fiber; 11 and 111, fibers in 
different degrees of degeneration; S, neurilemma; m, medullary sheath; 
A, axon; k, nucleus of neurilemma cell; L, marking of Lantermann ; R, node 
of Ranvier; mt, drops of myelin; a, remains of axon; w, proliferating cells 
of neurilemma. 

Fig. 332 shows one of the main nerves of the pulp, extending to the 
center where it branches into two distinct trunks. An artery faintly 
outlined may be seen behind the nerve trunk which also bifurcates like 



DEVELOPMENTAL PATHOLOGY 



the vessels being cut in such a way as to show the outer walls running 
parallel with the nerve trunk. The single vessels show the corpuscles 
plainly. The nerve trunk consists of the number of medullated nerve 
fibers. Internodes can be plainly seen in some of them. In some nerve 
fibers, variocosity or Wallerian degeneration is plainly seen. Internodes 
or Ranvier's nodes are also plainly seen. The basal structure of these 
illustrations is seen only partially or not at all, as they are stained specially 
to bring out nerve fibers. 

Fig. 333. The nerve trunks show the medullated character very 
well, many nodes of Ranvier being in evidence. Varicosities and various 




Figure 329 
Microscopic section of dental pulp showing active inflammation and breaking down of tissue, 
formation of abscess at apical end of root (original) . X 50. 



degrees of degeneration can be followed in the individual fibers. In a few 
fibers, the darker axis cylinders with a higher stained primitive sheath are 
also seen. The various coats of the artery show the nuclei cut in trans- 
verse or vertical directions. 

Fig. 334. The nerve fibers here present a much more swollen and 
thickened appearance than in Figs. 332 and 333. The nuclei of the fibers 
show clearly and also varying degrees of thickening. Some fibers show 



A STUDY IN DEGENERATIVE EVOLUTION 395 

the nerve. The vasomotor track is well marked by the circular coat of 
drops of myelin or Wallerian degeneration. The upper bundle of fibers 
has become thickened and sclerosed. The basal structure with connective 
tissue fibers and cells is better shown than in the other illustrations. 

Fig. 335. In this illustration appears a large nerve trunk much 
increased in size and ending almost abruptly like a neuroma in an amputa- 




Figure 330 
Microscopic section of dental pulp showing pulp stones and abscess in three different stages 
(original). A, shows active round cell inflammation; C, an abscess fully formed; B, 
cicatrical tissue of healed abscess. X 450. 



tion. The basal structure is much altered, being of a chronic interstitial 
variety. There are few, if any connective tissue cells, but well, marked 
bands of fibrous tissue. The individual nerve fibers show interruptions 
by the intermixing of the fibrous stroma, thus altering their function. 
The fibers are varicosed and vary in thickness. 

I have demonstrated the vasomotor system and nerve endings in the 
arteries of the pulp, which together with nerve end degeneration and the 
blood are the three sources by which any and all diseases and poisons of 
the body may affect the pulp and thus lessen the resistance of tooth struc- 
ture. 



396 



DEVELOPMENTAL PATHOLOGY 



Thrombosis. Among vascular changes and circulatory disturbances, 
thrombosis in the blood vessels of the pulp is not uncommon. From the 
present knowledge of pathology and the pathogenic condition of the pulp, 
it is evident how thrombosis must occasionally result. The pulp, an end 
organ without anastomosis and collateral circulation, the blood returning 
through a single vein, creates an anatomic predisposition for formation 

HI 







Figure 331 
Diagrammatic illustration of a healthy nerve and nerve degeneration (Ziegler). This illustra- 
tion is partly schematic and shows Wallerian degeneration of nerve fibers after section. 
Thoma. I, normal nerve fiber; II and III, fibers showing different degrees of degenera- 
tion; S, neurilemma; m, medullary sheath; A, axon; k, nucleus of neurilemma cell; L, 
marking of Lantermann; R, node of Ranvier; mt, drops of myelin; a, remains of axon; 
w, proliferating cells of neurilemma. 



of a thrombus. The many degenerations and retrogressive changes which 
take place in the pulp make it susceptible to this morbid state. The 
spontaneous death of the pulp which sometimes follows disease can be 
thus accounted for. Formation of different calcic deposits causes the 
current to become slower and the leucocytes to be retarded in their progress 
from and to the apical end of the root canal. In time the blood plates 
separate from the blood current and are caught at the apical end of the 



A STUDY IN DEGENERATIVE EVOLUTION 



397 



pulp canal. Sudden blindness occurs under similar conditions. The 
vessels become injured or abnormal, due to calcic deposits and other retro- 
gressive changes and stasis take place, eventually furnishing a basis for 
future thrombosis and inflammation (Fig. 336). 

A thrombus may be located in any part of the arterial system, but 
more especially the heart. Simple or septic fragments may become dis- 
lodged and carried through the blood streams to or into the pulp of the 
tooth. Having entered this cavity, its return is almost impossible. 

Embolism consists of various structures, such as fat drops, tissue 
fragments, tumor cells, air, etc. These follow the blood current. The 




Figure 332 
Microscopic section of dental pulp showing nerve end degeneration (original). 



X143. 



size of the body regulates the distance to which an embolus may travel. 
It stops in vessels whose lumen prevents its passage. More frequently it 
is arrested at the bifurcation of the artery. The pulp is especially adapted 
for this purpose, since it is an end organ, with numerous loops terminating 
in one or more veins for exit. 

Emboli, according to Hektoen, act in two ways, mechanically, clogging 
the circulation, and specific, depending on the nature of the embilus, 
whether infected or sterile, whether composed of dead or living cells, 
capable of further proliferation. The circulation may be mechanically 



398 DEVELOPMENTAL PATHOLOGY 

obstructed. If septic material has lodged in a blood vessel, inflammation 
may extend to the surrounding tissues (Fig. 337) . 

Endarteritis Obliterans and Arterio-sclerosis. Inflammation 
of the arterial coats in the pulp is very common. This is due, in a degree, 
to pulp embryogeny, anatomy, environment and to its end-organ nature, 
as already stated. The diseases most commonly observed are endarteritis 
obliterans, arterio-sclerosis. While it is not uncommon for each coat of 
the artery to take on a special type of inflammation, yet all frequently 
become involved. 

Endarteritis obliterans is an inflammation of the inner coat of the 
artery, usually of a chronic type. The inflammation may arise from an 







Figure 333 
Microscopic section of dental pulp showing nerve end degeneration (original). X 162. 

irritant in the blood current from the main current, through the vaso 
vasorum or through the lymphatics. The first is the most usual; in the 
alveolar process all three may occur. In the pulp, irritation in the blood 
stream is the most common method. Proliferation of the endothelium 
results. Bands of fibrous tissue develop. The blood vessels become 
obstructed and finally obliterated, impeding the circulation (Fig. 338). 

The structure pulp, made up of loops of blood vessels and situated 
within bony walls, with only one or two arteries and veins for the passage 



A STUDY IN DEGENERATIVE EVOLUTION 399 

of blood, renders it a unique end organ, and its arteries susceptible to 
arterio-sclerosis. This, together with endarteritis obliterans, predispose 
the arteries to degeneration and necrosis. This is a thickening of the 
arterial walls, especially of the intima. It is secondary, according to Hek- 
toen, to certain inflammatory or degenerative changes in the media. This 
is seldom observed early in life. It is commonly found after puberty, 
but more frequently at the senile stage, from forty years on. The causes 
producing arterio-sclerosis in other parts of the body produce it in the 
pulp arteries. 

The causes are usually autointoxication and drugs taken into the 
system, which likewise become irritants. Beside the distensive force and 




Figure 334 

Microscopic section showing three bundles of nerve fibers with Wallerian degeneration and 

foci of inflammation (original). X 156. 

change in composition of the blood, local irritation on the arterial wall is 
an active cause. In disease such as syphilis, gout, rheumatism, Bright 's 
disease, alcoholism and chronic mercurial, lead, brass, arsenic and bromide 
poisoning the walls become irritated, resulting in thickening of the arterial 
coats. 

"The inebriate, whose brain and body after death exhibit a confused 
mass of wreckage, which the pathologist is often unable to trace back to 
the exact causes and conditions, has, according to Crothers, always sclerotic 



400 DEVELOPMENTAL PATHOLOGY 

conditions of the large and small arteries, together with atrophic and 
hyperatrophic states of the heart, kidneys and liver, with fatty degenera- 
tion and calcification of the coats of the arteries. These organic changes 
are so frequently present in inebriates that they constitute a marked 
pathology which is traceable to the use of alcohol. " 

These irritants, acting through the vasomotor system and increasing 
the arterial pressure, finally cause paralysis and diminution of the caliber 




Figure 335 

Microscopic section of the dental pulp showing nerves in the arterial coats of arteries and also 

a large nerve trunk showing Wallerian degeneration (original). X 143. 

of the arteries and capillaries, producing stasis of blood (Fig. 339). This 
morbid state of the arteries tends to produce any or all of the other degen- 
erations previously referred to. 

The inflammatory process of the intima was first charged to direct 
irritation of material floating in the blood. Rokitansky and Thoma are 
of opinion that it is secondary and dependent on the degenerative changes 
of the middle coat. This view I can not accept, since autointoxic states 
produce irritation in the blood streams. 

Many degenerations of the pulp are the result of arterio-sclerosis, 
endarteritis obliterans and nerve degeneration. These degenerations occur 
in connection with each other; in other words, sometimes two, three and 
even more are to be found in the same pulp. The causes producing these 
degenerations are not understood. 



A STUDY IN DEGENERATIVE EVOLUTION 



401 



Retrogressive Changes. One direct result of arterio-sclerosis and 
endarteritis obliterans is cloudy swelling and fatty degeneration. These 
conditions are observed in connection with such diseases as typhoid fever, 
septicemia and other acute infections and toxic diseases. The tissues 
present a whitish or shiny appearance, without fibrous structures. Under 
the microscope the tissues present an opaque mass and do not take stain. 
The cells are quite large and swollen (Fig. 340). 

"When a tissue, as for instance the heart muscle, receives a diminished 
quantity of blood on account of the narrowing of the lumen of the arteries 
due to thrombosis, embolism or disease accompanied by thickening of the 




, : r; 






Figure 336 
Microscopic section of dental pulp showing thrombosis of the capillaries and inflammation 
(original). Arteries and capillaries are closed. The acute inflammation shows there 
has been an hyperemic condition. X 137. 

intima, albuminous and fatty changing, remarks Hektoen, usually result. 
In the case of the different forms of anemias, degenerations with fat pro- 
duction are found in the liver, heart, kidneys and muscles. In such con- 
ditions there is not enough oxygen and other nutritive material to maintain 
the function of the cells. In actual starvation there is first absorption of 
all the fat in the body, accompanied by a marked diminution of the struc- 
ture. In the later stages, albumin and fatty degeneration take place. 
Albuminal and fatty changes are very common in febrile diseases. They 
occur in practically infectious diseases and in a large number of the intoxi- 



402 



DEVELOPMENTAL PATHOLOGY 



cations, such as the drug poisons. They are also found in abnormal 
metabolism, due to direct action of poisons and the abnormal process of 
oxidation." Owing to the pulp's peculiar structure and environment, 
fatty degeneration is commonly found in its tissue (Fig. 341). 

Amyloid degeneration is a peculiar degeneration of the connective 
tissue, causing an albuminous substance to be deposited in the surrounding 
tissue. The walls of the blood vessels also become involved. It presents 
a shiny appearance and differs from other tissues in that it turns a dark 




Figure 337 
Microscopic section of dental pulp showing dilated vessel, diapedesis and embolus. X 280. 



red color with iodin. The morbid state is found in syphilis, tuberculosis, 
chronic dysentry, etc. (Fig. 342). 

Almost every structure in the body may be involved. 

Hyaline degeneration (Fig. 343) is, according to Stengle, closely 
allied with amyloid, mucoid and colloid degeneration, and all can pass 
into each other. It can occur in tissues during infectious and septic 
processes, following traumatism, in autointoxications such as drug poison, 



A STUDY IN DEGENERATIVE EVOLUTION 



403 



hemorrhages in cicatrices, in senile blood vessels, arterio-sclerosis, endarter- 
itis obliterans and in the nervous system. It can also occur in connective 
tissue which has undergone a change by inflammation. This morbid 
state depends for its action on local or general nutritive disturbances. 
The pulp, therefore, is susceptible to it. The intima, as well as the entire 
walls of the small blood vessels in the pulp, easily becomes involved. 
Some investigators believe that fat connective tissue cells so arrange 






Figure 338 
Microscopic section of dental pulp showing endarteritis obliterans (original). The wall in 
one artery is thickened (endarteritis) and almost occluded by inflammatory products. 
In the smaller artery the intima contains round-celled infiltration, almost occluding it. 
The pulp tissues show the myxomatous character very well, branched spindle and round 
nucleated cells in many places. X 225. 



themselves as to undergo a change into myaline substances (Fig. 344). 
These ultimately lead to calcification. 

Calcic Deposits. This raises the question of calcic deposits or 
so-called pulp stones. Pathologists know that tissues elsewhere in the 
body (which have necrosed or degenerated) are the localities where lime 
salts are deposited. Dying tissue which has undergone more or less 
change possesses, according to Ziegler, a kind of attraction for the lime 
salts in solution in the body. The tissues, to which attention has been 
called, are especially susceptible to calcic changes ; hyaline and fatty degen- 



404 



DEVELOPMENTAL PATHOLOGY 



eration, tissues involved in disease or drug poisoning, already mentioned 
here and elsewhere. Regions affected by slight degeneration and in struc- 
tures like the pulp, a constricted end organ, are predisposed to deposits of 
lime salts. Calcic deposits have different shapes and location in the pulp 
tissue. Circumscribed structures appearing solid under the miscroscope, 
to the naked eye or to the touch, are not pulp stones or calcic deposits, but 
in a large percentage of cases belong to other retrogressive changes. These 
deposits (Fig. 345) are, no doubt, due to degeneration of pulp tissue, 
especially in structures undergoing hyaline or fatty degeneration. Large 




Figure 339 
Microscopic section of dental pulp showing enlarged artery in early stages of thickening 
(original). The small vessels are plugged up; there is well marked myxomatous pulp 
tissue. X225. 



masses of deposits in the form of spherules often occur. Bone formations 
are sometimes observed. These deposits, both in pulp stones and spherules, 
take on a dirty, bluish-violet color, with hematoxylin. These Dr. Latham 
and I have observed many times. Crystals may sometimes occur. 

"This applies, however, as Ziegler remarks, only to deposits of lime 
carbonates and phosphates and not to those of lime oxalate." These 
deposits may take place at any time, but are most likely at the senile or 
fourth period of stress. 

Fibroid Degenerative growth of the pulp may be both rapid or 
slow. Inflammatory reaction in fibrous pulps is rare, although when 



A STUDY IN DEGENERATIVE EVOLUTION 



405 



followed by infection or exposure, it may take place. Various degeneracies 
like those already mentioned are liable to occur, especially those in which 
connective tissue in general is predisposed. The fibers are observed in 
bundles, closely packed together, with many connective tissue corpuscles 
shown at intervals. Fibroid degeneration is easily distinguished from 
the other degeneracies of the pulp (Fig. 346). 

In these cases, the blood vessels and nerve tissue are relatively few. 
The blood vessels remaining usually have thickened walls, especially in 




Figure 340 
Microscopic section of dental pulp showing pulp stones (original). The pulp stones are 
scattered throughout; here and there a form of round celled infiltration, longitudinal 
trunks, few degenerated vessels surrounded by hyaline degeneration in the middle of 
nerve trunk; early sclerosis and cloudy swelling or granular degeneration; adontoblasts 
in situ. X 21. 



the external and middle coats. This, of course, narrows the lumen. Not 
infrequently the blood vessels are entirely obliterated. These fibromas, 
very common in exposed pulps, are not now under consideration. In 
nearly if not all of these degenerations the blood vessels are first involved, 
later nerve tissue. 



406 DEVELOPMENTAL PATHOLOGY 

All these degenerations, including the pathologic processes of evolution, 
are the direct constitutional causes of tooth decay, erosion and abrasion 
brought about by diminution of tooth vitality. 

Summary 

The pulp is developed from the dental papilla derived from the mucosa 
beneath the basement membrane, which differs from the enamel organ in 
possessing arteries, veins, and nerves. 

In the teeth of the lower animals the pulp is as large as the base of the 
tooth, furnishing complete nourishment, but as the species ascend, 'the 




Figure 341 
Microscopic section of dental pulp showing fatty degeneration (original) . In this illustration 
are also seen beside fatty degeneration, acute pulpitis, sclerosis of nerves, nerve degenera- 
tion, dilation of vessels, faint outline of degenerated adontoblasts. X 137. 

pulp contracts at the neck until in the human teeth they are nearly closed, 
making of the tooth a foreign body and the pulp itself a characteristic 
end-organ. 

Under unstable nervous system or other defects various abnormalities 
occur in the dentine development, either phylogenetic or ontogenetic in 
nature, producing teeth that are prone to decay. 

The question of lymphatics in pulp is as yet unsettled, but experi- 
ments demonstrate that a drainage does exist, and that pulps do repair 
themselves after decay and abscesses. 



A STUDY IN DEGENERATIVE EVOLUTION 407 

The teeth are furnished with a very complete system of vasomotor 
nerves, entering and emerging through the apical foramina, the number 
depending upon the size of the foraminal opening. As man advances in 
age and exostosis, the opening naturally grows smaller. 

i The causes which bring about diseases of the pulp consist of changes 
in the blood current, due to circulating poisons, resulting from degenerative 
conditions occurring at periods of stress. 

Pathologic degeneration of the pulp begins when it has ceased to form 
dentine and the apical end is nearly closed, rendering it a typical end-organ 




^Z: 



Figure 342 ^ 

Microscopic section of dental pulp (original). Shows pulp stones and their close relation to 
the vascular channels. Dilated vessels with amyloid deposit. X 62. 

enclosed within bony unyielding walls, where it cannot expand and where 
the high blood pressure of toxic conditions easily ruptures the vessels. 
No other part of the body is so susceptible to local hyperemia and pressure 
necrosis. And on the other hand, no part is so liable to constriction 
anaemia, with its constricted neck and its terminal arteries having no 
anastomosis. 

All these conditions of the pulp are readily produced or accentuated 
by the action of the vasomotor system upon its terminal arteries. 



408 



DEVELOPMENTAL PATHOLOGY 



Inflammatory processes in the pulp may pass through all the stages, 
from infection to abscess, without pain. 

Thrombosis is not uncommon in the pulp, formed by the lodgement 
of simple or infective matter in the vessels, due to the friction of calcic 
deposits, and accounts for frequent apparently spontaneous death of the 
pulp. The lack of anastomosis and collateral circulation, and the return 
of the blood through a single vein, renders the pulp specially favorable to 
thrombosis. 




¥ 



Figure 343 
Microscopic section of dental pulp (original). Shows calcareous deposit, medullary nerve, 
early connective tissue formation. X 225. 



Embolism not infrequently occurs in the pulp from the same causes 
to which, being an end-organ with numerous vascular loops, it is peculiarly 
liable. 

The same end-organ conditions make the pulp a frequent seat of 
endarteritis obliterans, due to irritants in the blood stream or the lympha- 
tics. Degeneration and necrosis of the pulp of course ensue. The under- 
lying causes are autointoxication resulting from diseases such as syphilis 



A STUDY IN DEGENERATIVE EVOLUTION 409 

gout, rheumatism, Bright 's disease, alcoholism and poisoning by various 
metals and drugs. 

Cloudy swelling, amyloid, hyaline and fatty degeneration, such as 
occur in the kidneys, take place equally and under the same conditions 
in the tooth pulp. 

Just as necrosed or degenerated tissues elsewhere in the body are the 
seat of calcic deposits, so the pulp under similar conditions becomes the 




Figure 344 

Microscopic section of dental pulp (original). Shows medullary nerve fibers, internodes, 

axis cylinders, myalin degeneration. X 280. 

seat of so-called pulp stones, which are most likely to occur at the fourth 
or senile period of stress, because lime salts are then in process of absorp- 
tion. 

All these forms of degeneration, together with the pathologic processes 
of evolution, are the direct causes of tooth decay. 



410 



DEVELOPMENTAL PATHOLOGY 




Figure 345 
Microscopic section of dental pulp (original) . Shows medullary nerve fibers slightly thickened. 
The connective tissue is degenerating and hyaline adontoblasts show well on both 
surfaces. X 156. 



A STUDY IN DEGENERATIVE EVOLUTION 



411 




Figure 346 
Microscopic section of dental pulp (original) . Shows interstitial fibrosis with acute inflamma- 
tory cells. Odontoblasts have been destroyed. X 22. 



Chapter XXIX 
THE EFFECTS OF PULP DISEASE ON TOOTH STRUCTURE 

DISEASES of the tooth pulp produce disastrous results on tooth 
structure. These resultant conditions consist in soft teeth, 
erosion, abrasion, discoloration, and a want of tooth resistance 
to the ravages of decay. 

In Chapter XXV, "The Vertebrate Teeth," it was shown that the 
teeth, in their ontogeny, at the first period of stress, passed through their 
phylogeny; that arrests in phylogeny occur as in other structures of the 
body. The jaws and teeth occasionally become arrested in their phylo- 
geny, at the higher mammal stage (lower savage), and develop large. 
The teeth are then hard, dense and perfectly formed. These may be 
considered hard teeth; they rarely decay or become soft and abrasion and 
erosion are rarely seen except in the most severe forms of disease. 

After the pulp has finished its work of forming dentine, it still has a 
slight physiologic function, in that it gives life to the dentine through the 
dental pulp and fibrillae. These fibrillae extend through the dentine to 
the periphery. 

Andrews states that "when the tooth is fully formed, the principal 
function of the pulp is for vitalization of the substance of the dentine, 
by means of its fibrils, which permeate into every portion of the matrix 
of the dentine. Its function is not only to vitalize, but it may again 
assume its formative function whenever causes for repair demand this. 
. . . We cannot look on its tissue in life, . . . conclusions must be 
drawn from what is shown to have taken place when the tissue was alive; 
the living pulp, with its blood vessels and nerves, nourishes the dentine; 
vital changes do take place, and the pulp is the source of vital action. 
It is a living organ, subject to any physiologic or pathologic process which 
may act on any living matter; its connection with the general economy 
must be similar to that of other tissues. It will respond to the action of 
returning health and caries which has commenced has been arrested by 
this vital action, appearing as polished blotches on the teeth, which are 
not uncommon. 

Miller, in his work on Micro-Organisms of the Human Mouth, calls 
this condition a spontaneous healing of dental decay. The dentine, 
which had become softened, has become hard again, and the decaying 
process is stopped. This change also takes place in the temporary teeth. 
The healed dentine retains its discolored appearance, but becomes nearly 
as dense as normal dentine. These changes have been brought about by 
vital action and this action came from the agency of the pulp. 

412 



A STUDY IN DEGENERATIVE EVOLUTION 413 

When the dentine is irritated by infection or its surface is uncovered 
by a break, there immediately follows a period of vital activity. If sections 
of a tooth made when these changes are taking place be examined, the 
formative cells in that portion of the pulp nearest the point of repair are 
found filling up with glistening globular bodies and the tissue about it is 
showing an increased vascularity, as though active formative action were 
taking place." 

Andrews was satisfied that these appearances were the result of the 
vital action of the pulp in its efforts to repair the tissue and that the 
minute glistening particles within the canals were in many ways similar 
to the minute globular bodies found in the tissues while the dentine matrix 
was developing. 

"The protecting consolidation is found in teeth that are worn down, 
usually in the mouths of old people, and when this change has taken place 
these teeth are not liable to decay again, except under very favorable 
circumstances .... These changes are due in a large measure to nor- 
mal conditions as regards the vitality of the individual; but in cases where 
the constitutional condition is below the normal, even where conditions 
seem favorable to decay, there is always an attempt made to retard the 
infection. Under certain conditions of environment and infection, pene- 
trating decay is so rapid that the vital action of the pulp is overwhelmed, 
and the pulp becomes exposed and is in a pathologic condition even before 
the breaking away of the cavity walls. 

"The pulp is the central and largest source of vitality to the tooth, 
and it acts through its myriads of fibrils .... Pain of the dentine 
following the touch of an instrument or from any irritation is expressed 
through the agency of these fibrils, and we become conscious of the sensa- 
tion through them The dentine is and was meant at all times to 

be a living tissue. It receives impressions of injuries and responds by 
processes of repair. Some of the ablest men in the profession have ques- 
tioned the further value of the tooth-pulp after the full formation of the 
tooth has taken place. They look on it simply as a formative organ and 
consider its mission closed with the formation of the tooth. It is, there- 
fore, in their judgment quite as well to destroy it, take it out and fill its 
chamber. The microscopic appearance of dentine after the pulp is removed 
shows that a large amount of dead organic tissue is left within the canals 
that cannot be taken out, and the dead tissue is a source of considerable 
danger to the health and vitality of the pericementum .... With 
death of pulp, not only is sensation in the dentine lost but also all the 
changes which vitality gives to an organ, such as nutrition and recupera- 
tion. " 

It is a well known fact that as man grows older, although in apparently 



414 DEVELOPMENTAL PATHOLOGY 

normal health, his teeth discolor; erosion and abrasion also occur, and in 
some patients, instead of the teeth remaining hard and without decay, 
decay is rapidly causing the teeth to disintegrate. 

As a general thing, patients go to the office of the dental specialist 
only when purely dental treatment is required. Rarely is he called when 
the patient is ill at home. The dental specialist, therefore, is not made 
aware that bodily disease is undermining the system of his patients, because 
when he sees them, they appear strong, from a physical standpoint, whereas 
they are really sensitive and defective in vitality. A patient may have 
faulty metabolism and autointoxication and yet live to a good old age, 
but the teeth will under these conditions, discolor and disintegrate early 
in life. These systemic conditions, indeed, first manifest themselves in 
the mouth, jaws and teeth. 

The changes, then, which bring about loss of sensation and vitality, 
causing a want of proper nutrition and recuperation, are faulty metabolism, 
autointoxication and neurasthenia, which in them produce poisons circu- 
lating in the blood, impoverished blood, and nerve end degeneration. 

First to be considered of these conditions are the metabolic toxemias 
and the autointoxications. Metabolic toxemias are those bodily poisons 
which arise from the body proper in the blood, tissue, and organs. Auto- 
intoxications are those poisons which arise from the gastro-intestinal tract, 
which are within the body and yet are not of the body. 

Metabolic Toxemias. The cells of the body are the unit of bodily 
activity. In health, they repair, increase, and propagate themselves. 
When the eliminatory organs, the skin, lungs, bowels, or. kidneys fail to 
perform their functions normally every cell is subjected to toxic influence. 
These body cells then become poisoned, and toxic conditions of the blood 
result. Disease, in children or adults, will also produce bodily poisons. 

Autointoxication. The dietetic question is one of vital importance 
to each individual; while in the growing child plenty of good nourishing 
food is essential to the welfare of the body, yet when the body has attained 
its full growth a lessened amount of food will keep the body well nourished. 
When more food is taken into the system than can be digested and assimi- 
lated, "high livers" as they are called, become overfed, the waste products 
are retained in the alimentary canal, and the toxins, by fermentation and 
putrefaction produce bad results upon the individual. So intensified may 
these toxins become, that death not infrequently results. Poisons due to 
autointoxication are best observed in an examination of the urine, the two 
most important symptoms being indicanuria and excessive urinary acidity. 

Toxins from both faulty metabolism and autointoxication, if not 
properly eliminated, will produce changes in the blood stream, resulting 
in disease of some one or all of the tissues of the body. Owing to location, 



A STUDY IN DEGENERATIVE EVOLUTION 415 

shape, or peculiar anatomy, some structures are more quickly involved 
in disease than others. 

Such structures are the transitory and end organs. The dental pulp, 
as has been shown, is the most perfect specimen of this type of organ in 
the human body. The trouble may be so widespread as to involve the 
pulp as a whole, thus causing the entire tooth to become involved, or only 
certain areas of the pulp are affected, in which case only certain parts of 
the crown become discolored or softened. The poisons, circulating in the 
blood, cause all the diseases enumerated in Chapter XXVIII, "The Dental 
Pulp." The dental fibrillae are destroyed, and nourishment of that part 
of the tooth is cut off. Tooth resistance is thus destroyed. Discoloration 
and tooth softening now take place. Friction, from any substance, readily 
wears the soft portions of the tooth away, causing erosion and abrasion, 
both being arrest in phylogeny as far back as the adult reptilian hatteria. 
Tooth decay results from external causes from want of tooth resistance. 
We must not lose sight of the fact that the teeth of children with an un- 
stable nervous system are not well developed in structure because the 
line salts have been diverted to other tissues (the brain and skull) under 
the law of economy of growth. This fact is well illustrated in those teeth 
(especially molars) which tend to conate (Figs. 269, 274 and 281) and in 
which owing to very imperfect structure decay takes place rapidly. 

Neurasthenia is a common neurosis by which, Preston remarks, 
males are equally affected with females. It is a nerve instability to which 
in addition to ordinary nerve fatigue there is a morbid susceptibility to 
emotions and inability to restrain their manifestations. It is apt to make 
its onset near puberty when permanent teeth are most liable to decay. 
Temporary teeth are frequently badly discolored, softened and decayed 
as a result of child neuropathy, hysteria, and disease. Permanent teeth 
later in life decay from premature senile neuropathy. Neurotic inheritance 
aided by the influence of climate and race tendencies, and anunstable, 
badly organized or imperfectly developed nervous system, are potent 
factors in tooth decay. When to this are added diatheses like tuberculosis, 
syphilis, etc., causes for tooth softening, discoloration and decay are 
enormously increased. Any long-continued disease, grief, worry, starva- 
tion, fear of litigation or death, also cause faulty metabolism, autointoxica- 
tion and excessive nerve fatigue, an excessive nerve waste and its retention. 
Anxiety, especially of young children, and between the ages of twelve and 
twenty-four, relative to their standing in school, is a fruitful source of 
nerve tire, nerve waste, and faulty metabolism. The forcing system of 
schools adds neurasthenia to the lists of accomplishments. While "all 
work and no play makes Jack a dull boy" from nerve tire and self -poison- 
ing, the same is even more true of Jack's sister. Few universities do not 



416 DEVELOPMENTAL PATHOLOGY 

have in their faculties fairly typic neurasthenics from pedagogic worry 
and too one-sided life. 

The causes just enumerated are in adults fruitful sources of nerve 
exhaustion. Elsewhere I have frequently shown that any excess is a 
fecund cause of nerve exhaustion. Neurasthenia occurs in every walk 
of life. People raised in luxury and idleness are the most evident victims 
of neurasthenia. The lowest classes, who give free rein to the appetites, 
and the tramps are often neurasthenics, as are those between these two, 
persons who lead a sedentary life to which is added severe mental strain, 
care, responsibility, monotony, anxiety. Neurasthenia is frequent among 
clerks, teachers, literary workers, etc. It is often the ancestral phase of 
degeneracy; through it occurs the rapid decay of the teeth in persons over 
thirty or forty years of age who have had very little decay previously. 

The local causes are thereby accelerated. In all the cases enumerated, 
either the nervous system or blood supply or both are involved. While 
all of these lesions are observed early in life, they are most active after 
forty years of age. It is especially at the senile stage — the fifth period 
of stress, or period of involution, when the excretory organs, from overwork 
or nerve tire, cause faulty metabolism and autointoxication — that the 
teeth undergo changes indicated by rapid decay, discoloration, erosion 
and abrasion. 

Changes taking place in tooth-structure must necessarily occur either 
in the blood stream or nerve tissue. Investigations of nerve lesions have 
demonstrated that in most diseases, nerve-end degeneration takes place, 
as Sidney Kuh has shown. In some of the toxic forms, as, for instance, 
in neuritis due to poisoning with lead and arsenic, the cells of the spinal 
cord as well as those of the spinal ganglia and brain may be diseased and 
the toxic substances may attack these cells before the nerve fiber itself 
is altered. This hypothesis explains why pronounced degeneration of 
peripheral nerves occurs without causing any appreciable symptoms. 
Pitres and Vaillard first showed that after typhoid fever many nerve fibers 
are found degenerated in cases where, during life, symptoms of neuritis 
were absent. The same observer found like states in the nerves of those 
who had died from tuberculosis. Later observations have extended these 
conditions to such diseases as diphtheria, syphilis, alcoholism, carcinoma, 
inanition, marasmus, arterio-sclerosis, and leprosy; in the so-called rheu- 
matic neuritis of the facial nerve, and in inflammation due to articular 
rheumatism, gout, puerperal infection, tuberculosis, etc. 

The method of cell-poisoning has been observed in other intoxications. 
Certain groups of neurons are more susceptible than others to a given 
intoxication. The same group of nerve cells in two individuals may react 
very differently to similar doses of the poison. The syphilitic toxin shows 



A STUDY IN DEGENERATIVE EVOLUTION 417 

a decided preference for certain parts of the cerebral cortex, other areas 
being less affected. The nerve endings in all parts of the body are markedly 
involved, especially those in and about the teeth. Peripheral nerve 
degeneration results where the blood current or the nerves themselves are 
involved from faulty metabolism, neurasthenia, etc. 

If disease affects nerve endings elsewhere in the body, it is but reason- 
able to believe that nerve endings, blood vessels and connective tissue in 
the pulp will likewise be involved, since the pulp is an end organ situated 
within bony walls, and a transitory structure is doubly susceptible to 
disease. The tooth pulp as has been shown is at its highest physical 
development when it commences to form dentine. From that time it 
degenerates; it begins to lose its blood supply and its nerve energy. As 
age advances, the blood and nerve supply is almost at a minimum. Is 
it surprising that so few pulps are found in normal condition? 

Dr. Vida A. Latham and myself have made a special study of dental 
pulp pathology. The results of our efforts have been presented before the 
Section on Stomatology of the American Medical Association and published 
in the Journal of that organization. 

A few illustrations will not be out of place at this time. 

In any public institution for degenerate children the teeth will be 
found badly decayed. Teeth of degenerate children living at home decay 
faster than those of healthy children of the same family. Teeth of pregnant 
women decay faster than before pregnancy. At the senile period or the 
period of involution under mental strain teeth decay rapidly. 

A forty-six-year-old woman had two sons and a daughter. The 
daughter at eighteen was attacked by peritonitis and died within a week. 
From persistent grief of the mother the teeth, previously in good condition, 
presented in eight months many cavities. Erosion, abrasion and dis- 
coloration followed. 

A forty- two-year-old woman was well-to-do financially. Her husband 
had charge of her property. She went abroad for two years and he was 
to bring her home at the end of that period. He failed to do so and kept 
her abroad for two years more. Remittances becoming short, she returned 
to find that her husband had squandered all her property, so she obtained 
a divorce. Resultant worry, as dermatologists would believe, turned her 
hair white. There was likewise marked recession of the alveolar process 
and gums from interstitial gingivitis as well as rapid decay of the teeth. 

The teeth of a thirty-five-year-old woman became soft and decayed 
rapidly from deep grief over the sudden death of her husband. 

Grief from its trophic results causes abrasion and erosion. The most 
marked cases are those occurring from death of husband, wife or children 
or loss of wealth. Drilling into pulp cavities of these types is often done 



418 DEVELOPMENTAL PATHOLOGY 

without pain or hemorrhage; pulps are removed without pain and with 
little hemorrhage; marked changes take place in enamel and dentine; the 
tissues not infrequently become softened; the incisors break off near the 
gum under pressure. All of these states occur in neurasthenia and melan- 
cholia. 

A forty-eight-year-old newspaper owner and editor became post- 
master of a large city. Resultant mental strain produced neurasthenia, 
with interstitial gingivitis and rapid decay of the teeth. Here the teeth 
were normally hard as flint, the enamel cut with difficulty, the dentine was 
as hard as the enamel. When the extra nerve strain was applied the 
enamel became brittle and the dentine cut like horn or old cheese. 

Tooth decay occurs much more rapidly when neurasthenia is present, 
irrespective of the cause. 

The teeth of paretic dements and tabetics decay rapidly. People 
who possess neurotic tendencies and inherited taint from consanguineous 
marriages or excesses suffer from tooth decay and irregularities. Severe 
illness will cause tooth decay and change the color to a dirty yellow, regard- 
less of age, softening tooth structure. In hemiatrophy tooth decay and 
interstitial gingivitis occur on the affected side and perhaps to a lesser 
extent on the other. In heart lesions (fatty degeneration, valvular disease, 
etc.) decay is rapid. Syphilitic and tubercular patients have tooth decay 
and interstitial gingivitis, while tooth erosion, abrasion and discoloration 
also occur in relation to nerve disorder and disease. 

The cutting or wearing away of the anterior teeth by the tooth brush 
below the enamel on the lower jaw and above the enamel on the upper is 
no doubt due to a softening of the dentine from systemic and internal 
causes. Such teeth are easily cut with bur, excavator or drill. Their 
pulps are less sensitive and bleed less than normal in removal. 

A boy with sound healthy enamel after recovery from pelvic abscess 
complained of his teeth feeling gritty. Dr. P. J. Kester found that the 
enamel had disintegrated. 

In typhoid fever, the enamel becomes brittle and cleaves from about 
fillings and decayed edges. On the grinding surface of the teeth of those 
of middle-age, especially neurotics, the enamel wears away and the dentine 
is hollowed out as in erosion. Teeth which are soft with chalky enamel 
at one period may on the other hand become hard with organized enamel 
at a later period and stop decaying. 

Dr. G. D. Boak states as to Philippine climatic effects upon the teeth: 
"While the weather is by no means as hot as it is at times during the 
summer in the States, the average temperature for the islands is about 
89° F. It is a continuous heat without invigorating change of seasons. 
This gradually saps vitality and enervates, producing the lassitude which 



A STUDY IN DEGENERATIVE EVOLUTION 419 

is characteristic of the tropics. Enervation produces anemia, with cor- 
responding lessening of the resisting powers from the lower vitality, especi- 
ally in those who have lived previously in temperate climates. Caries is 
frequent and progresses rapidly in this climate. " This Dr. Boak attributes 
to the following causes: First, lowering of the vitality by a lessening of 
the resisting powers; second, acidity of the oral secretions. 

A strong, healthy young man of Irish parentage, twenty-one years of 
age, has been under my care for some years. He is of more than ordinary 
intelligence, perfectly healthy, and of an athletic build. His jaws measure 
two and one-half inches from the buccal surfaces of the first molars. He 
had thirty-two good, sound, hard teeth without a cavity. He contracted 
lues. In two years, his teeth softened with rapid decay, erosion, abrasion, 
discoloration and interstitial gingivitis. At the end of six years, the 
diseases have been arrested as well as the interstitial gingivitis, but the 
teeth still remain soft, and the usual history of decay is progressing. This 
is a typical but not uncommon case of hard teeth made soft by disease. 

A typical illustration of soft teeth is that of a twenty-seven-year-old 
travelling salesman, one of my patients, who had a severe attack of jaundice 
one year ago. He came to have his teeth put in order. I found they had 
become yellow and soft; decay was progressing rapidly about the fillings; 
in excavating the cavities, there was no pain; the fibrillae were destroyed; 
if the pulps could be examined, they would be found diseased and receding 
in the pulp chamber. 

It is not uncommon to find soft temporary teeth quite yellow, decaying 
rapidly and fibrillae and pulps destroyed: Master J. S. seven years of age, 
had measles at five. Recovery was slow; at seven is not strong. The 
permanent first molars, centrals and laterals are in place and are of a 
fairly good quality. The temporary cuspids, first and second temporary 
molars are soft, decay rapidly, pulps are reached without pain and the 
teeth are quite yellow. 

I have a record of a number of like little patients. They have all had 
eruptive fevers and some have inherited disease. 



Summary 

Diseases of the tooth pulp cause discoloration, softening, erosion, 
abrasion, and diminish tooth resistance against rapid tooth decay. 

When the dental pulp has finished its work of dentine formation it 
still retains its function of keeping the dentine alive. 

Andrews and Miller have shown that soft teeth become hard; that 



420 DEVELOPMENTAL PATHOLOGY 

this nourishment is carried in the blood through the pulp by the dental 
fibrillae to the tooth substance. 

Changes in density take place in the temporary as well as the perma- 
nent teeth. 

The formation cells in that portion of the pulp nearest the point of 
repair are filled with new material for the purpose of repair. This repair 
is noticeable in some of those teeth which are worn down in old age. In 
most people, however, as age advances, the eliminating organs gradually 
become senile, and are sluggish, hence poisons remain in the system. 

The dental specialist is not aware of the serious results which are 
progressing in the mouth and teeth because the patient does not appear 
to be ill. He is not ill, in a manner of speaking, because there are no 
ordinary symptoms of disease, yet from a stomatologic standpoint the 
early symptoms of disease are markedly present, as demonstrated by the 
condition of the jaws and teeth. 

Metabolic toxemias and autointoxication poison the blood when 
more food is taken into the system than can be appropriated. These 
symptoms can best be studied by an examination of the urine. The two 
most important indications are indicanuria and excessive urinary acidity. 
Unless these symptoms be corrected serious conditions result. Their 
effect upon the pulp is to cause nerve-end degeneration, abscess and other 
degenerate states. When the indicanuria and excessive acidity are restored 
to normal, the blood, as a rule resumes its proper function. 

The location, shape and peculiar structure of the dental pulp make it 
a favorable organ for disease. Its transitory and end-organ conditions 
cause it to be the most perfect tissue in the human body for the attacks 
of disease. 

Diseases may be so severe as to involve the entire structure causing 
death of the entire pulp, or only circumscribed areas may become involved. 
Hence the entire tooth may discolor, soften, erosion and abrasion may 
result or decay may be very rapid. Again only certain areas of tooth 
structure may be involved. 

Neurasthenia alone may cause nerve-end degeneration, destroy the 
fibrillae in the dental tubuli, and produce the same results. Neurasthenia 
may be acquired in the parent and transmitted to the child, or the child 
may acquire the disease. People with a nervous breakdown have diseased 
jaws and teeth. 

Persistent grief and worry will so change the secretions of the body as 
to bring on faulty metabolism and excessive urinary acidity. Excessive 
mental strain will produce like results. 

Degenerate children are more frequently observed with soft and 
decayed teeth than the non-degenerate. 



A STUDY IN DEGENERATIVE EVOLUTION 421 

The teeth of paretic dements and tabetics soften and decay rapidly. 
Severe illnesses will cause pulp destruction, tooth softening, erosion, 
abrasion, discoloration and tooth decay. 

^ ! Climatic changes, such as those with which the soldiers contended in 
the Philippines and Cuba, cause lowered vitality and lessened resistance 
power, which bring about auto-intoxication, resulting in change of tooth 
structure through the dental pulp. 



BIBLIOGRAPHY 



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2. R. R. Andrews, The Vital Action of the 

Dental Pulp. 

3. Frank Baker, The Ascent of Man. 

4. F. M. Balfour, A Treatise on Compara- 

tive Embryology. 

5. D. G. Brinton, Races and Peoples. 

6. Paul Carus, The Soul of Man. 

7. Arthur Clarkson, A Text-book of 

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8. Edward Clodd, The Story of Primitive 

Man. 

9. Edward Clodd, A Primer of Evolution. 

10. A. DeQuatrefages, The Natural His- 

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11. E. D. Cope, The Primary Factors of 

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12. Charles Darwin, The Origin of Species. 

13. Charles Darwin, The Descent of Man. 

14. Charles Darwin, Animals and Plants 

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15. J. D. Dana, New Text-book of Geology. 

16. Bashford Dean, Fishes, Living and 

Fossil. 

17. DeMoor, Evolution by Atrophy. 

18. J. W. Draper, History of the Intellect- 

ual Development of Europe. 

19. H. H. Donaldson, The Growth of the 

Brain. 

20. R. L. Dugdale, The Jukes. 

21. Henry Drummond, The Ascent of Man. 

22. Havelock Ellis, Man and Woman. 

23. Havelock Ellis, The Criminal. 

24. Louis Figuier, Mammalia: Their Vari- 

ous Forms and Habits. 

25. John Fiske, The Destiny of Man. 

26. John Fiske, Excursions of an Evolu- 

tionist. 

27. Enrico Ferri, Criminal Sociology. 

28. Austin Flint, A Text-book of Human 

Physiology. 

29. Sir W. H. Flower, Osteology of the 

Mammalia. 

30. Sir W. H. Flower, An Introduction to 

the Study of Mammals; Live and 
Extinct. 

31. Theodore Gill, The Families of Fishes. 

32. Theodore Gill, Articles on Fishes in 

the Riverside Natural History. 

33. John C. Galton, Ecker's The Human 

Brain. 

34. Francis Galton, Hereditary Genius. 

35. Francis Galton, Natural Inheritance. 

36. C. Gegenbaur, Elements of Compara- 

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in the department of Geology and 

Palaeontology. British Museum 

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of Sex. 
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Limb Dwarf. 
T. H. Huxley, Anantomy of Vertebrated 

Animals. 
T. H. Huxley, Man's Place in Nature. 
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Biology. 
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David J. Hill, Genetic Philosophy. 
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G. Kiernan, Mixoscopic Adolescent 

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423 



424 



BIBLIOGRAPHY 



74. Sir Charles Lyell, Principles of 

Geology. 

75. Joseph LeConte, Evolution and Its 

Relation to Religious Thought. 

76. Joseph LeConte, Elements of Geology. 

77. Willoughby Miller, Micro-organisms 

of the Human Mouth. 

78. C. S. Minot, Human Embryology. 

79. C. K. Mills, Brains of Criminals. 

80. St. George Mivart, The Genesis of 

Species. 

81. St. George Mivart, Lessons in Ele- 

mentary Anatomy. 

82. St. George MivART,The Common Frog. 

83. St. George Mivart, The Cat. 

84. A. M. Marshall, Vertebrate Embryo- 

logy. 

85. McMurrich, The Development of the 

Human Body. 

86. C. Lloyd Morgan, Animal Life and 

Intelligence. 

87. C. Lloyd Morgan, Animal Biology. 

88. Osborn, From the Greeks to Darwin. 

89. Osler, Modern Medicine. 

90. Richard Owen, Anatomy of Verte- 

brates. 

91. Richard Owen, Odontography. 

92. A. S. Packard, Zoology. 

93. Charles A. Parker, Wormian Bones. 

94. Parker and Haswell, Text-book of 

Zoology. 

95. Oscar Peschel, The Races of Man. 

96. Piersol, Anatomy. 

97. E. P. Potjlton, The Colours of Animals. 

98. Gtjstav Preiswork, Atlas and Text- 

book of Dentistry. 

99. Th. Ribot, Heredity. 

100. G. J. Romanes, Darwin and After Dar- 

win. 

101. S. H. Reynolds, The Vertebrate 

Skeleton. 

102. Roux. The Struggle for Existence 

between Organs. 

103. Salter, Dental Pathology and Surgery. 

104. Oscar Schmidt, The Mammalia. 

105. Oscar Schmidt, Descent and Darwin- 

ism. 

106. Schafer and Thane, Quain's Elements 

of Anatomy. 

107. Karl Semper, Animal Life. 

108. Herbert Spencer, Principles of Bi- 

ology. 

109. E. C. Spitzka, Somatic Etiology of In- 

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110. W. B. Scott, An Introduction to 

Geology. 

111. N. S. Shaler, First Book in Geology. 

112. Sudduth, American System of Dentist- 

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113. J. B. Sutton, Evolution and Disease. 

114. D. Kerfoot Shute, A First Book in 

Organic Evolution. 

115. R. S. Tarr, Elementary Geology. 



116. J. A. Thomson, Outlines of Zoology. 

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118. E. B. Tylor, Anthropology. 

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120. Carl Vogt, Lectures on Man. 

121. Charles Ward, Human Teeth from 

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BIBLIOGRAPHY 

The following books and monographs of 
the author have been drawn on largely for 
material in compiling the present edition. 

Books 

1. The Irregularities of the Teeth, First 

Edition, 1888. 

2. The Irregularities of the Teeth, Second 

Edition, 1890. 
3 Chart of Typical Forms of Irregularities 
of the Teeth, 1891. 

4. A Study of the Degeneracy of the Jaws 

of the Human Race, 1892. 

5. The Etiology of Osseous Deformities of 

the Head, Face, Jaws, and Teeth, 
Third Edition, 1894. 

6. Degeneracy: Its Signs, Causes and Re- 

sults (London), 1898. 

7. Interstitial Gingivitis or So-called Pyor- 

rhoea Alveolaris, 1899. 

8. Irregularities of the Teeth, Fourth Edi- 

tion, 1901. 

9. Quiz Compend of Irregularities of the 

Teeth, 1901. 
10. Irregularities of the Teeth, Fifth Edition, 
1903. 

Monographs 

1. Education, Dental Colleges — The Den- 

tal Cosmos, 1876. 

2. Mercury, Chemical and Physiological 

Action of Fillings on the System — 
The Denial Cosmos, 1879. 



BIBLIOGRAPHY 



425 



3. Preparation of Nerve Canals for Treat- 

ment and Fillings — The Dental Cos- 
mos, 1880. 

4. Gold Crowns— The Dental Cosmos, 1880. 

5. Screws for Artificial Crowns — The Den- 

tal Cosmos, 1881. 

6. Treatment and Filling of Approximal 

Cavities — The Dental Cosmos, 1881. 

7. The Regulation of Teeth by Direct 

Pressure — The Dental Cosmos, 1881. 

8. Dental Regulating Apparatus — The Den- 

tal Cosmos, 1885. 

9. Spreading the Dental Arch — The Dental 

Cosmos, 1886. 

10. Regulating Individual Teeth — The Den- 

tal Cosmos, 1886. 

11. Pyorrhoea Alveolaris, 1st Paper — The 

Dental Cosmos, 1886. 

12. The Etiology of Irregularities of the 

Teeth,— The Dental Cosmos, 1888. 

13. Arrest of Development of the Maxillary 

Bones, due to Race Crossing, Climate, 
Soil and Food — The Dental Cosmos, 
1888. 

14. Development of the Inferior Maxilla 

by Exercise and Asymmetry of the 
Lateral Halves of the Maxillary Bones 
— The Dental Cosmos, 1888. 

15. Asymmetry of the Maxillary Bones — 

The Dental Cosmos, 1888. 

16. The Alveolar Process — The Dental Cos- 

mos, 1888. 

17. The Origin and Development of the V 

and Saddle Arches and Kindred 
Irregularities of the Teeth, — The 
Dental Cosmos, 1889. 

18. The Above Concluded— The Dental 

Cosmos, 1889. 

19. Classification of Typical Irregularities 

of the Maxillae and Teeth — The Den- 
tal Cosmos, 1889. 

20. Satistics of Constitutional and Develop- 

mental Irregularities of the Jaws and 
Teeth of Normal, Idiotic, Deaf and 
Dumb, Blind and Insane Peisons — 
The Dental Cosmos, 1889. 
21 Fallacies of Some of the Old Theories of 
Irregularities of the Teeth with Some 
Remarks of Diagnosis and Treatment 
— The Dental Cosmos, 1890. 

22. The Teeth and Jaws of a Party of Cave 

and Cliff Dwellers — The Dental Cos- 
mos, 1890. 

23. The Differentiation of Anterior Protru- 

sions of the Upper Maxilla and Teeth, 
International Medical Congress, Ber- 
lin— The Dental Cosmos, 1890. 

24. Mouth-Breathing not the Cause of Con- 

tracted Jaws and High Vaults — The 
Dental Cosmos, 1891. 

25. Management of Dental Societies — The 

Dental Cosmos, 1891. 



26. 

27. 
28. 
29. 

30. 

31. 

32. 

33. 
34. 

35. 

36. 
37. 



39. 
40. 



41. 



42. 



43. 



44. 

45. 



46. 
47. 



Studies of Criminals — The Alienist and 
Neurologist, 1891. 

Scientific Investigation of the Cranium 
and Jaws — The Dental Cosmos, 1891. 

Evidence of Somatic Origin of Inebriety 
— Journal of Inebriety, 1801. 

A Study of the Degeneracy of the Jaws 
of the Human Race — The Dental 
Cosmos, 1892. 

Empyema of the Antrum — Journal of 
the American Medical Association, 
1893. 

The Vault in its Relation to the Jaw and 
Nose — The Dental Practitioner and 
Advertiser, 1894. 

Stigmata of Degeneracy in the Aristo- 
cracy and Regicides — Journal of the 
American Medical Association, 1894. 

The Degenerate Ear — Journal of the 
American Medical Association, 1895. 

Pyorrhoea Alveolaris, 2nd Paper — In- 
ternational Dental Journal, 1896; The 
Dental Cosmos, 1896. 

Dental and Facial Evidence of Constitu- 
tional Defect — The International Den- 
tal Journal, 1896. 

H. H. Holmes — Journal of the American 
Medical Association, 1896. 

Pyorrhoea Alveolaris, 3rd Paper — Jour- 
nal of the American Medical Associa- 
tion, 1896. 

Degeneracy of the Teeth and Jaws — 
Journal of the American Medical 
Association, 1896. 

Oral Hygiene — International Medical 
Congress, Moscow, 1897. 

Autointoxication in its Medical and 
Surgical Relations to the Jaws and 
Teeth — Journal of the American Med- 
ical Association, 1897. 

Pyorrhoea Alveolaris in Mercurial and 
Lead Poisoning and Scurvy, 4th Paper 
— Journal of the American Medical 
Association, 1898. 

Degeneracy in its Relation to Deformi- 
ties of the Jaws and Irregularities of 
the Teeth— The Chicago Dental Re- 
view, 1898. 

A Study of the Stigmata of Degeneracy 
among the American Criminal Youth 
— Journal of the American Medical 
Association, 1898. 

Irregularities of the Dental Arch — 1898. 

A Study of the Deformities of the Jaws 
among the Degenerate Classes of 
Europe — The International Dental Jour- 
nal, 1898. 

Inheritance of Circumcision Effects — 
Medicine, 1898. 

What Became of the Dauphin Louis 
XVII? A Study in Dental Jurispru- 
dences — Medicine, 1899. 



426 



BIBLIOGRAPHY 



48. Interstitial Gingivitis due to Autointoxi- 

cation — The International Dental Jour- 
nal, 1900. 

49. Traitement de la Pyorrhie Alveo-dent- 

aire — XIII International Medical Con- 
gress Proceedings, Paris, 1900. 

50. The Intervention of Therapeusis in 

Anomalies of Position and Direction 
of the Teeth — XIII International 
Medical Congress Proceedings, Paris, 
1900. 

51. Limitations in Dental Education — 

Journal of the American Medical 
Association, 1900. 

52. Interstitial Gingivitis from Indigestion 

Autointoxication — Journal of the Amer- 
ican Medical Association, 1900. 

53. Interstitial Gingivitis as a Prominent 

Obvious Early Symptom of Autoin- 
toxication and Drug Poisoning — 
Chicago Medical Society Proceedings, 
1901. 

54. Peridental Abscess — Proceedings New 

York State Dental Society, 1901 . The 
Chicago Dental Review, 1901. 

55. Oral Manifestations and Allied States 

— Journal of the American Medical 
Association, 1901. 

56. Degeneracy and Political Assassination 

— Medicine, 1901. 

57. The Higher Plane of Dentistry — Revue 

de Stomatologic, Paris, 1902. 

58. Juvenile Female Delinquents — The Ali- 

enist and Neurologist, 1901-2-3. 

59. The Stigmata of Degeneracy — The Med- 

cal Examiner and Practitioner, 1902. 

60. Deformities of the Bones of the Nose 

and Face — The Laryngoscope, 1902. 

61. Evolution of the Pulp — Journal of the 

American Medical Association, 1902. 

62. Why Dentists do not Read — The Inter- 

national Dental Journal, 1903. 

63. How Far do Stomatologic Indications 

Warrant Constitutional Treatment? 
— The International Dental Journal, 
1903. 

64. Syphilitic Interstitial Gingivitis — The 

International Dental Journal, 1903. 

65. Gum Massage — The International Dental 

Journal, 1903. 

66. The Vasomotor System of the Pulp — 

Journal of the American Medical 
Association, 1903. 

67. Recognition of the D. D. S. Degree by 

the American Medical Association — 
Dental Journals, 1903. 

68. What the Physician or Surgeon should 

know of Dentistry — Illinois Medical 
Bulletin, 1903. 

69. Pathogeny of Osteomalacia or Senile 

Atrophy — Journal of the American 
Medical Association, 1904. 



70. Constitutional Causes of Tooth Decay 

— The Dental Digest, 1903. 

71. Interstitial Gingivitis or So-called Pyor- 

rhoea Alveolaris — The Dental Sum- 
mary, 1903. 

72. Buccal Expressions of Constitutional 

States — Medicine, 1903. The Dental 
Digest, 1903. 

73. Endarteritis Obliterans and Artero- 

Sclerosis of the Alveolar Process — 
The Dental Digest, 1903. 

74. Pathology of Root Absorption and Alveo- 

lar Abscess — The Dental Digest, 1904. 

75. The Relations of the Nose and Genitalia 

— Medicine, 1904. 

76. Pulp Degeneration — Journal of the Amer- 

ican Medical Association, 1904. 

77. Criminal Responsibility and Degener- 

acy — British Medical Association, Sec- 
tion on Psychological Medicine, 1904. 

78. Anatomic Changes in the Head, Face, 

Jaws and Teeth in the Evolution of 
Man — Fourth International Dental 
Congress, St. Louis, Mo., 1904. 

79. Constitutional Causes of Tooth Decay, 

Erosion, Abrasion and Discoloration 
— Fourth International Dental Con- 
gress, St. Louis, Mo., 1904. 

80. Etiology of Cleft Palate— Fourth Inter- 

national Dental Congress, St. Louis, 
Mo., 1904. 

81. Scorbutus or Interstitial Gingivitis — 

Medical News, 1904. 

82. Negro Ethnology and Sociology — Illi- 

nois Medical Bidletin, 1905. 

83. Gonorrhoeal Ulcero-Membraneous Sto- 

matitis — The International Dental 
Journal, 1905. 

84. Evolution of the Central Nervous Sys- 

tem— The Dental Digest, 1905. 

85. Study of the Pithecanthropus Erectus 

or Ape- Man — The International Den- 
tal Journal, 1905. 

86. Advance and Retrogressive Evolution 

— The Dental Digest, 1905. 

87. Underlying Factors of Developmental 

Pathology or Suppressive Evolution 
— The Dental Digest. 1905. 

88. Laws Governing Eugenesis: A Thirty- 

five Years Study of Developmental 
Pathology— The Dental Era, 1905. 

89. Developmental Pathology and Tooth 

Decay— The Dental Cosmos, 1905. 

90. Errors in Dental Education — The Dental 

Cosmos, 1906. 

91. Interstitial Gingivitis due to Autoin- 

toxication: Etiology — The Dental Di- 
gest, 1906. 

92. Interstitial Gingivitis due to Autoin- 

toxication as Indicated by the Urine 
and Blood Pressure: Diagnosis — The 
Dental Digest, 1906. 






BIBLIOGRAPHY 



427 



93. Therapeusis and Treatment of Intersti- 

tial Gingivitis due to Autointoxication 
— The Dental Digest, 1906. 

94. Acid Autointoxication and Systemic 

Disease the Cause of Erosion and 
Abrasion — Proceedings of the New York 
State Dental Society, 1907. 

95. Alcohol in its Relation to Degeneracy — 

Journal of the American Medical 
Association, 1907. 

96. Acid Intoxication or Acidosis: A Factor 

in Disease — New York Medical Re- 
cord, 1907. 

97. Stomatology in its Medical Aspects — 

Extrait du Bulletin of the International 
Association of Stomatology, Bruges, 
1908. 

98. Swan Songs and Degeneration of Ameri- 

can Dental Colleges — The Dental 
Cosmos, 1908. 

99. The Care of the Teeth— Illinois Medi- 

cal Bulletin, 1908. 

100. Etiology of Face, Nose, Jaw and Tooth 

Deformities — Journal of the American 
Medical Association, 1909. 

101. Bone Pathology and Tooth Movement 

— Journal of the American Medical 
Association, 1909. 

102. Acidosis, Indicanuria, Internal and 

External Secretions; the Effects upon 
the Alveolar Process and Teeth — 
The Dental Cosmos, 1908. 

103. Sense and Nonsense as taught in Ameri- 

can Dental Schools — The Dental 
Cosmos, 1909. 

104. Treatment of Interstitial Gingivitis — 

The Dental Cosmos, 1909. 

105. Progress of Stomatology in Europe — 

The Dental Cosmos, 1909. 

106. Hard Teeth and Soft Teeth— The Dental 

Cosmos, 1909. 

107. Progress of Stomatology in Hungary — 

American Journal of Clinical Medicine, 
1909. 



108. Local Manifestations of Systemic Dis- 

eases — XVI International Medical 
Congress, Budapest, 1909. 

109. How Shall the Stomatologist be Edu- 

cated? — International Association of 
Stomatology, Budapest, 1909. 

110. Scope of Developmental Pathology — 

The Alienist and Neurologist, Feb. 1910. 

111. Rip Van Winkles in American Dental 

College Faculties — The Dental Cosmos, 
1910. 

112. The Scope of Developmental Pathology 

in its Relation to Oral Manifesta- 
tions — International American Con- 
gress of Medicine and Hygiene, 1910. 

113. Oral Hygiene in American Dental 

Schools — The Dental Cosmos, 1910. 

114. The Academic Condition — The Medical 

Standard, 1910. 

115. Iodin as an Astringent, Antiseptic, 

Disinfectant and Germicide in the 
Treatment of Mouth Diseases — 
Journal American Medical Associa- 
tion, 1910. 

116. How Shall the Stomatologist be Edu- 

cated? — Journal American Medical 
Association, 1910. 

117. Care of the Mouths of School Children 

— The Dental Summary, 1910. 

118. The Quality of Service Rendered — The 

Dental Summary, 1910. 

119. What are Dentists as a Profession do- 

ing to Advance their Specialty? — The 
Dental Summary, 1910. 

120. Treatment to Alleviate the Contagions, 

Infections and Local Diseases of 
School Children — The Dietetic and 
Hygienic Gazette, 1910. 

121. Developmental Pathology: A Study 

in Degenerative Evolution — Proceed- 
ings of the First District Dental So- 
ciety of New York, 1910. 

122. The Future of Dentistry — Sunday 

Editorial in The Chicago Tribune, 1911 . 



INDEX 



Abnormality, Median Suture, 284. 
Abscess, Dento-Alveolar, 263, 272. 

Peridental, 267, 270, 272 

in Pulp, 387. 
Absence Lower Jaw, 216. 
Abuse, Coffee, 112 

Tea, 112. 

Tobacco, 109, 110, 111. 
Achrondoplasia, 137. 
Acraniata, Kidney of, 52. 
Actor, Skull, 174. 
Additional Cusps to Teeth, 344. 
Adipose Tissue, 12. 
Alcohol, 111. 
Alveolar Hypertrophy, 289. 

Process, 224, 226, 235, 240. 

Deformities, 291. 

Development, 292. 
Amoeba, 4, 5. 
Amphibia, Heart of, 38. 
Amphibia, Kidney of, 52. 
Amyloid Degeneration of Pulp, 402. 
Anal Arrest, 144. 
Anaptomorphus, 345. 
Angle, Facial, 165. 
Annelid Heart, 38. 
Anthropoidae, 326. 
Anthropoid Nose, 187. 
Antlers, 12. 

Antrum, Degeneracies, 205, 208. 
Antrum, Diseases, 207. 
Antrum, Types, 204. 
Aorta, 38. 

Ape, Anthropoid, 24. 
Ape, Brain, 30, 33. 
Ape, Phylogeny, 24. 
Appendix, Vermiform, 162. 
Archaeopteryx, 316. 
Arches, Dental, 218. 
Arrest, Brain, 35, 102. 

Development, 97, 98. 

Face, 170, 288. 

Heart, 45. 

Kidney, 5Q. 

Nose, 186, 189, 192, 198. 

Snout, 187. 

Teeth, 339, 364, 369. 
Arrested Heart Types, 45. 
Arteriosclerosis of Pulp, 399. 
Asymmetry, Brain, 102. 
Atavism, 90. 

Attachment, Teeth, 329, 332. 
Autointoxication, Pulp in, 400. 
Aztec Nose, 187. 
Baleen, 321. 
Batrachian Heart, 39. 
Bats, 323. 



Bat Teeth, 323. 
Bibliography, 423. 
Biconodont, 345. 
Bird, 

Brain of, 29, 33. 

Heart of, 39, 40. 

Kidney of, 53. 

Liver of, 47 . 

Teeth of, 314, 316, 371, 375. 
Birth Stress, 92. 
Blastula, 9. 

Blastodermic Vesicle, 9. 
Blood, Cells, 12. 
Blood, Vessel Ontogeny, 41. 
Bones, 135, 136, 137. 
Bowel Degeneracy, 147. 
Brachycephaly, Vaults and, 281. 
Brain, 

Ape, 30, 33. 

Arrests, 35, 102. 

Asymmetry, 102. 

Bird, 29. 

Defects, 100, 139. 

Degeneracy, 99, 100. 

Degenerates, 35. 

Fetal, 34, 70, 100. 

Fibres of, 104. 

Fish, 29, 32. 

Ideal, 101. 

Idiot, 103. 

Imbecile, 103. 

Jaws and, 175. 

Lemur, 30, 33. 

Localization, 105. 

Mammal, 29. 

Man, 31, 32. 

Marsupial, 29, 33. 

Ontogeny, 32, 37. 

Phylogenv, 28, 36. 

Reptile, 29, 33. 
Brass, 114. 
Brass Poisoning, 251. 
Budding Cell, 4. 
Bunodontia, 326, 327. 
Calcic Deposits. 256, 259. 
Calcification of Teeth, 375. 
Cancer, 36. 

Canals, Haversian, 230. 
Canals Volkmann's Perforating, 231, 240. 

243. 
Canines, 326. 
Caraivora, 324. 
Cartilage, 12. 
Cavities, Orbital, 161. 
Cell, 

Blood, 12. 

Budding, 4. 



429 



430 



INDEX 



Cell, 

Differentiation, 10. 

Division, 3. 

Ectoplasm, 4. 

Germ, 2. 

Mesoblastic, 11. 

Nature of, 1. 

Nerve, 11. 

Potentialities, 23. 

Powers of, 13. 

Reproduction, 1. 

Structure, 2. 13. 
Cerebrum, 

Apes, 33. 

Bird, 33. 

Fish, 33. 

Lemur, 33. 

Marsupial, 33. 

Reptile, 33. 
Cerebellum, 34. 
Cetecea, 320. 

Chambers of Heart, 43, 44. . 
Chameleon, 345. 
Changes in Teeth, 183. 
Chick, Liver of, 47 
Children Degenerate, 93. 
Chorea, 93. 
Chromatin, 3. 
Chromosomes, 4, 6, 8. 
Chondrocranium, 60, 62. 
Cleft Palate, 293, 295, 299, 301, 302. 
Cleft Urogenital, 144 
Climate and Teeth, 419, 421. 
Clitoris Perforation, 93. 
Cloaca, 144, 146. 
Club Foot, 149. 
Club Hand, 149. 
Coca, 113. 
Coffee Abuse, 112. 
Concrescence, 363. 
Cone Teeth, 355. 
Conoid Teeth, 356, 359. 
Continuous Teeth, 374. 
Cranium Changes, 164. 
Crownless Teeth, 370. 
Cryptorchidism, 93, 146. 
Cusps, 359, 360, 362. 

Additional, 344. 

Anterior, 345. 

Human, 345. 

Lingual, 345. 
Cuspid Teeth, 367, 368. 
Cyclopia, 92, 160. 
Cyclops, 160. 
Cyclothymia, 93. 
Cylinders, Hepatic, 49. 
Cytoplasm, 4. 
Defects, Brain, 100. 

Ear, 99. 

Speech, 93. 
Deflection, Nose, 190, 196, 198. 
Deformed Vaults, 281. 



Deformities, 

Alveolar Process, 291. 

Vault, 299. 
Degenerative Influences, 84. 
Degeneracy, 93, 99, 122, 123, 129, 147, 149, 
151, 152, 153, 155, 163. 

Antrum, 205, 208. 

Bowel, 147. 

Bones, 135, 136. 

Brain, 99, 100. 

Evolution, 132. 

Face, 176. 

Hip Joint and, 148. 

Lipomatosis and, 93. 

Nose, 191. 

Teeth, 332, 359, 363, 372, 421. 

Thyroid and, 93. 

Toxic, 115. 
Dental Arches, 218. 
Dental Pulp, 375. 
Dentine, 377, 413. 
Dento-Alveolar Abscess, 263, 272. 
Deposits, Calcic, 256, 259. 
Desmid, 3. 
Deutoplasm, 6. 
Development, 

Alveolar Process, 292. 

Arrests in, 97, 98. 

Face, 76, 78, 79, 185. 

Jaw, 219. 

Skull, 61, 62, 63. 

Man, 3, 15. 

Neuron, 35. 

Nose, 77, 79, 186, 189. 

Nutrition and, 130. 

Organ, 28. 

Pulp, 406. 

Stress and, 34. 

Teeth, 220, 336. 
Diabetes, 270. 
Diatoms, 3. 
Differentiation, 362. 
Differentiation Cell, 10. 
Diseases of Antrum, 207. 
Dolichocephaly, Vaults and, 281. 
Dromatherium, 344. 
Dugong Teeth, 322. 
Durencephaly, 108, 133. 
Dysmenorrhea, Membraneous, 93. 
Ear Defects, 140, 142, 143. 
Echidna, 320. 
Echidna, Teeth of, 320. 
Economy of Growth, 95, 165. 
Economy of Growth, Law of, 19. 
Ectoderm, 10. 
Ectoplasm, 4. 
Egg-Nucleus, 7. 
Elephantidae, 325. 
Elephant Teeth, 325. 
Elongated Teeth, 370. 
Embolism, 397. 
Embryo, Man, 20. 



INDEX 



431 



Embryogen, 16. 

Man, 21. 

Skull, 71, 73, 74. 

Vertebrate, 16. 
Enamel, 338, 340, 346, 418. 
Endarteritis Obliterans, 249, 250. 
Endarteritis Obliterans, Pulp, 398. 
End Organs, 235, 415. 
End Organs, Alveolar Process, 234. 

Pulp, 377. 
Endoderm, 10. 
Endoplasm, 4. 
Epiblast, 10, 13. 
Epiblast, Structures, 13. 
Epilepsy, 93, 117. 
Epithelium, 10. 
Epithelium, Specialized, 10. 
Epithelial Cord, 336, 339. 
Eruption of Teeth, 228, 348. 
Evolution, 19. 

Degeneracy, 130. 

Face, 165, 167. 

Teeth, 345, 354, 359, 362. 
Excessive Development of Teeth, 368. 
External Nose, 200. 
Face, 

Arrests, 170, 288. 

Development, 76, 78, 185. 

Evolution, 165, 167. 

Ideal, 165. 

Kleptomanic, 176. 

Ontogeny, 170. 

Phylogeny, 65, 66, 67, 168. 

Structures, 92. 

Types, 170, 171, 174. 
Facial Angle, 165. 
Fatigue Signs, 94. 
Female Kidney, 55. 
Fetal Brain, 34, 100. 
Fetal Liver, 49. 
Fetal Neuroses, 125. 
Fibres in Brains, 104. 
Fibroids, Pulp, 405. 
Fingers, 138. 

Fish, Brain of, 29, 32, 33. 
Fish, Heart, 38. 
Fish, Teeth, 302, 307, 309. 
Food and Jaws, 184. 
Foot, Club, 149. 
Foot, Flat, 150. 
Frog, Liver of, 47. 
Gain and Loss, Kidney, 53. 
Gall Bladder, 49. 
Gall Duct Ontogeny, 49. 
Gatrula, 14. 
Gastrulation, 9. 
Generalized Reptiles, 24. 
Generalized Types, 24. 
Genius, One-sided, 176. 
Germ, Cell, 2. 
Germ, Teeth, 338. 
Gills, 38. 



Gill Clefts, 140. 
Gill Slits, 21. 
Gingivitis, 377. 

Interstitial, 233, 235. 

In Dogs, 240, 241. 
Goitre, 106. 
Gout, 94. 

Grasping Power of Infants, 156. 
Great Toe Muscles, 156. 
Gum Recession, 240. 
Hair, 139. 

Halisteresis, 240, 243. 
Haplodontia, 326. 
Harelip, 292, 294. 
Harlot, Skull of, 173. 
Haversian Canals, 230. 
Head, Ontogeny, 59. 

Phylogeny, 59, 65. 

Spermatozoon, 8. 
Heart, 

Amphibia, 38. 

Annelid, 38. 

Arrested, 45. 

Batrachian, 39. 

Bird, 39, 40. 

Chambers of, 43, 44. 

Fish, 38. 

Lancelot, 38. 

Ontogeny, 40, 42. 

Phylogeny, 38. 

Reptile, 39, 40. 
Hebephrenia, 93. 
Height of Vault, 273, 281. 
Hepatic Cylinder Ontogeny, 49. 
Heredity, 96, 115, 116, 90. 
Heredity, Toxic Causes, 117. 
Hesperornia, Teeth of, 315. 
Heterodont, 317. 
Hip Joint Degeneracy, 148. 
Homedont, 318. 
Homogenesis, 184. 
Homolecithal, 10. 
Howship 's Lacunae, 240. 
Human Tail, 149, 155. 
"Hutchinson" Teeth, 355, 357. 
Hyaline Degeneration of Pulp, 402. 
Hyaliplasm, 3. 
Hypertrophy, Nasal, 190. 
Hypoblast, 10, 13. 
Hypospadias, 92. 
Ichthyornis, Teeth of, 316. 
Ideal Brain, 101. 
Idiot Brain, 103. 
Idiocy, 172. 

Idiocy, Mongolian, 300. 
Imbecile, Brain, 103. 
Impressions, Maternal, 92, 127. 
Impregnation, Man, 7. 
Impregnation, Ovum, 7. 
Incisors, 326. 

Infant's Grasping Power, 156. 
Inflammation, Pulp, 386. 



432 



INDEX 



Influences, 

Degenerative, 84. 

Mechanic, 84. 

Nutritive, 84. 

Toxic, 84. 
Inhibition, 98, 109. 
Insane Criminal, 177. 
Insectivores, 323. 
Insolation, 115. 
Instability, 129. 
Instability, Nerve, 109. 
Intellect Types, 180. 
Internal Nose, 200. 
Interstitial Gingivitis, 233, 235. 
Jaw, 

Absence Lower, 215. 

Brain and, 175. 

Development, 219. 

Food and, 184. 

Ontogeny, 211. 

Sinuses, 204. 

Types, 183. 

Variability, 210. 
Kidney, 

Acraniata, 52. 

Amphibia, 52. 

Arrests, 55, 

Bird. 

Female, 55. 

Gain and Loss, 53. 

Mammal. 53. 

Ontogeny, 52. 

Reptile, 52. 

Shark, 52. 

Trout, 52. 
Kleptomaniac Face, 176. 
Lacuna, Howship's, 240. 
Lanugo, 139. 
Lawyer, Skull, 176, 180. 
Law of Economv of Growth, 19. 
Lead. 114. 
Lemur, 323. 

Brain, 30, 33. 

Teeth, 323. 
Leucocytes, 12. 
Lipomatosis, 92. 

Lipomatosis, Degeneracy and, 93. 
Lithemia, 251. 
Liver, 

Chick, 47. 

Fetal, 49. 

Frog, 47. 

Lancelot, 47. 

Lizard, 47. 

Mammal, 48. 

Ontogeny, 47, 50, 52. 

Phytogeny, 50, 52. 

Shark, 47. 

Trout, 47. 
Localization, Brain, 105. 
Lophodontia, 326. 
Long Crown Teeth, 368. 



Loss of Teeth in Man, 349. 
Lymphatics in Pulp, 377. 
Macrorhine Nose Type, 187. 
Malformation, 117. 
Malformed Teeth, 357, 358. 
Mammal, 143. 

Brain, 29. 

Kidney, 53. 

Liver, "48. 

Teeth, 317, 327, 329. 
Man, 

Brain, 31, 32. 

Development, 3, 15. 

Embryo, 20. 

Embryogeny, 21. 

Impregnation, 7. 

Infant, 26. 

Ontogeny, 15. 

Ovary, 6. 

Ovum, 6. 

Phytogeny, 15, 20, 23. 

Reproduction, 3. 
Manatee Teeth, 322. 
Marriage of Relatives, 118, 119. 
Marsupial, Brain of, 29, 33. 
Maternal Impressions, 92, 127. 
Maternal Vitality, 300. 
Maternity and Nutrition, 124. 
Mechanic Influences, 84. 
Median Suture, 291. 
Median Suture, Abnormality, 284. 
Membraneous Dysmenorrhea, 93. 
Menstruation, Irregular, 93. 
Mercurialism, 252. 
Mercury, 114. 
Mesoblast, 10, 13. 
Mesoderm, 10. 
Mesonephros, 54. 
Metanephros, 54. 
Metazoa, 1, 2. 
Miacia, 344. 
Mitosis, 3, 14. 
Molar Teeth, 371. 
Mongolian Idiocy, 300. 
Monkey Teeth, 325. 
Montremata, 318. 
Monstrosities, 184. 
Morula, 14 
Mouthbreathing, 189. 
Murderer, Skull of, 178. 
Muscles, 12. 
Myoscin, 12. 
Mystaceti, 321. 
Narwhal, 368, 369. 
Narwhal, Teeth of, 321. 
Nasal, 

Bones Length of, 189. 

Hvpertrophies, 189. 

Septum, 194, 201. 
Nasopithecus, 186. 
Natural Selection, 19. 
Necrosis, 267, 272. 



INDEX 



433 



Negro, Types, 181. 
Nerve , 

Cells, 11. 

Instability, 109. 

Nutrition, 106. 

Organ. 36. 

Pulp Degeneration of, 396. 
Neurasthenia, 109, 120, 416. 
Neurons. 138. 

Development, 35. 

Types, 35. 
Neuroses, 

Classification, 125. 

Fetal, 125. 
Nipples, 143. 

Non-development of Teeth, 375. 
Non-eruption of Teeth, 367. 
Nose, 

Anthropoid, 187. 

Arrests, 186, 189, 192, 196. 

Aztec, 187. 

Deflection, 190, 195, 197. 

Degeneracy, 190. 

Development, 77, 79, 186, 188. 

External, 200. 

Internal, 200. 

Macrorhine Type of, 187. 

Ontogenv, 81, 191. 

Phylogeny, 81, 186, 190. 
Notchord, 60. 
Nucleoli, 3. 
Nucleus, 3. 

Number of Teeth, 328, 331. 
Nutrition, 

Development, 130. 

Maternity and, 124. 
Nutritive Influences, 84. 
Nutritive Stress, 92. 
Obesity, 92, 151. 
Odontoceti, 321. 
Odontromes, 339. 
One-sided Genius, 175. 
Ontogeny vs. Phylogeny. 26 
Ontogeny, 15, 27, 3' 

50, 52,* 53. 58, 59, 

170, 189, 192, 211, 
Ooplasm, 6. 
Oosperm, 8. 
Opium, 109. 
Orbital Cavities, 161. 
Organ Development.. 28. 
Organ Nerves, 36. 
Ornithoryncus, 319, 375. 
Ornithoryncus, Teeth of, 319 
Osteoblasts, 12. 
Osteoclasts, 12. 
Ovary, 6. 
Ovum, 14. 

Impregnation, 7. 

Man, 6. 

Segmentation, 9. 
Palatometer, 273, 274. 



, 38, 40, 41, 46, 47. 49, 
68, 81, 94, 97, 98, 107, 
336, 339, 375, 376. 



Paretic Dementia, 

Pulp in, 418. 

Teeth in, 421. 
Pathology of Pulp, 375, 417. 
Perforating Canals, 240, 243. 
Perforation, Clitoris, 93. 
Periods of Stress, 83, 85, 88, 95. 
Permanent Teeth, 371. 
Peridental Abscess, 267, 270. 
Phocomelia, 137. 
Phvlogenv vs. Ontogenv, 25. 
Phylogeny, 15, 16, 17, 20, 23, 27, 28, 36, 38, 

45, 50, 52, 58, 59, 70, 81, 97, 98, 107. 152. 

170, 186, 191, 293, 336, 339, 364, 369, 371, 

375. 
Pineal Body, 92, 156, 159. 
Pithecanthropus, 67. 
Plastin, 3. 
Plumbism, 251. 
Polar Bodies, 6, 8. 
Politician, Skull of, 177. 
Potentiality, Cell, 23. 
Precocity, 92. 
Primary Skull, 60. 
Promammal Teeth, 344, 375. 
Pronephros, 53. 
Pronucleus, 7, 8. 
Protoplasm, 3. 
Protozoa, 1. 
Pseudopodia, 5. 

Psychic Causes, disease in pulp, 417. 
Ptychodontia, 326. 
Pulp, 

Alcohol and, 399. 

Amyloid Degeneration, 402. 

Arteriosclerosis, 399. 

Autointoxication, 400. 

Dental, 375. 

Development, 406. 

Disease, 412, 419. 

End Organ, 377. 

Endarteritis, 398. 

Fibroids, 405. 

Hyaline Degeneration, 402. 

Inflammation, 386. 

Lymphatics, 377. 

Nerve Degeneration, 393, 400. 

Ontogeny, 376, 377. 

Paretic Dementia, 418. 

Pathology, 375, 417. 

Phylogeny, 376. 

Retrogressive Changes, 401. 

Stones, 403. 

Tabes, 418. 

Vasomotor System, 377. 

Vessels, 378. 
Pus Infection, 260. 
Pyorrhea Alveolaris, 260. 
Quadrumana, 325. 
Relatives, Marriage of, 118. 119. 
Reproduction, Man, 3. 



434 



INDEX 



Reptiles, 

Brain, 29, 33. 

Heart, 39, 40. 

Generalized, 24. 

Kidney, 52. 

Teeth, 309, 311, 345, 375. 
Reversion, 131. 
Ribs, 161. 
Rodents, 322. 
Rodents, Teeth of, 322. 
Rootless Teeth, 370. 
School Strain, 94, 119. 
Scurvy, 250, 270. 
Segmentation, 9. 
Segmentation Ovum, 9. 
Senility, 92. 
Serrated Teeth, 367. 
Sets of Teeth, 372. 
Shedding Teeth, 248. 
Simiadae, 325. 
Siren, 138. 
Sirenia, 322. 
Skull, 59. 

Actor, 174. 

Business Type, 179. 

Criminal, 176, 177. 

Development, 61, 62, 63. 

Embryogeny, 71, 73, 75. 

Growth, 75. 

Harlot, 173. 

Insanity, 175. 

Intellect Type, 181. 

Lawyer, 176, 181. 

Murderer, 178. 

Negro Type, 181. 

Plates, 60. 

Politician, 177. 

Primary, 60. 

Secondary, 63, 64. 

Types, 80, 170, 172, 174, 176, 178, 180, 
182. 
Snout Arrests, 187. 
Speech Defects, 93. 
Spermatozoon, 7. 
Spermatozoon, Head, 8. 
Spina Bifida, 148. 
Spongioplasm, 3. 
Spreading Roots, 371. 
Stigmata, 130. 
Stigmata, Teeth and, 346. 
Stress, 

Birth and, 92. 

Development and, 34. 

Nutritive, 92. 

Periods of, 83, 85, 88, 95. 
Supernumerary Teeth, 350, 352, 371, 374. 
Syphilis, 254, 300, 356. 
Syphilitic Teeth, 356. 
Tail, Human, 149, 155. 
Tea Abuse, 112. 
Teeth, 

Arrests, 339, 364, 368. 



Attachment, 328, 331. 

Bat, 323. 

Bird, 313, 314, 316, 375. 

Calcification, 375. 

Carnivore, 324. 

Changes, 183. 

Climate and, 419. 

Cine, 355. 

Conoid, 356, 359. 

Constitutional Disease and, 375. 

Continuous, 374. 

Cuspid, 367, 368. 

Degeneration, 332, 359, 372, 421. 

Development, 219, 335. 

Disappearance, 349, 354. 

Dugong, 322. 

Echidna, 320. 

Elephant, 325. 

Elongated, 370. 

Eruption, 228, 349. 

Evolution, 345, 354, 359, 362. 

Excessive Development of, 368. 

Fish, 302, 307, 309, 375. 

Germs, 338. 

Hesperornis, 315. 

"Hutchinson," 355, 357. 

Ichthyomis, 316. 

Insectivore, 323. 

Lemur, 323. 

Long Crown, 368. 

Loss of, in Man, 349. 

Malformed, 357, 358. 

Mammals, 317, 327, 329. 

Manatee, 322. 

Molar, 371. 

Monkey, 325. 

Narwhal, 321. 

Non-development of, 375. 

Non-eruption of, 367. 

Number, 328, 331. 

Ontogeny, 335, 338. 

Ornithoryncus, 319. 

Paretic Dement, 421. 

Permanent, 371. 

Phylogeny, 335, 339, 368, 370. 

Primitive, 372. 

Promammal, 344, 375. 

Pulp Disease and, 412. 

Reptile, 309, 311, 345, 375. 

Rodents, 322. 

Roots, 266, 272. 

Rootless, 370. 

Serrated, 367. 

Sets of, 372. 

Shark, 350. 

Shedding, 348. 

Soft, 419. 

Spreading Roots of, 371. 

Stigmata, 346. 

Supernumerary, 350, 352, 371, 374. 

Syphilitic, 356. 

Tabetic, 421. 



INDEX 



435 



Temporary, 349. 

Undeveloped, 370. 

Ungulates, 322. 

Union, 364, 366. 

Use of, 328. 

Vertebrate, 302. 
Telolecthal, 10. 
Teratology, 118. 
Thyroid Degeneracy, 93. 
Tobacco, 111. 
Tobacco, Abuse, 109*. 
Toxemia, 414. 
Toxic Degeneracy, 115. 
Toxic Influences, 84. 
Transplantation Viscera, 45. 
Traumatism, 115. 
"Tree of Life," 22. 
Turbinates, 192, 201. 
Types, 

Antrum, 203. 

Business, 178, 179. 

Generalized, 24. 

Intellect, 180. 

Jaw, 183. 

Skull, 80, 170, 172, 174, 176, 17) 
182. 

Macrorhine Nose, 187. 

Negro, 181. 



180, 



Neuron, 35. 

Vault, 273, 291. 
Ungulates, 322. 
Union of Teeth, 363, 365, 366. 
Urogenital Cleft, 144. 
Use of Teeth, 328. 
Uterus, 146. 

Vasomotor System of Pulp, 377. 
Vault, 

Brachycephaly, and, 281. 

Deformed, 281. 

Deformities of, 299. 

Dolichocephaly and, 281. 

Height of, 273, 281. 

Race and, 281. 

Types of, 273. 
Veins, 38. 

Veins, Ontogeny, 41. 
Vermiform Appendix, 162. 
Vertebrates, Embryogeny, 16. 
Vertebrates, Teeth, 302. 
Viscera Transplantation, 45. 
Vitality, Maternal, 300. 
Vitellus, 6. 

Volkmann's Perforating Canals, 230. 
Von Ebner Vessels, 230. 
Yolk Elements, 9. 
Zona Pellucida, 6. 



DEC 11 1911 



One copy del. to Cat. Div. 

ffr- 



